SecProbe.io

CORRESP
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MFS®
INVESTMENT MANAGEMENT

111 Huntington Avenue, Boston, Massachusetts 02199

Phone
617-954-5000

July 30, 2024

VIA EDGAR (as Correspondence)

United
States Securities and Exchange Commission

100 F Street, N.E.

Washington,
DC  20549

RE: Registration
Statement on Form N-1A for MFS Active Exchange Traded Funds Trust (the "Trust") on behalf of MFS Active
Core Plus Bond ETF, MFS Active Growth ETF, MFS Active Intermediate Muni Bond Fund ETF, MFS Active International
ETF, and MFS Active Value ETF (each a “Fund” and collectively the "Funds") (File Nos. 333-278691
and 811-23953)

Ladies and Gentlemen:

 On
behalf of the Trust, this supplemental letter sets forth our responses to the comments of the staff of
the U.S. Securities and Exchange Commission (the “Staff” or the “SEC”) received by letter dated
May 14, 2024 (the “SEC Letter”), regarding the above-referenced Registration Statement (the "Registration
Statement"), which was filed with the SEC on April 15, 2024. The Registration Statement was filed for
the purpose of registering the Trust and registering the Funds as series of the Trust. For your convenience,
each comment is included below, followed by the MFS Investment Management (MFS) response. Any term that
is used, but not defined, in this letter retains the same meaning as used by MFS in the Registration
Statement.

 As requested in the
SEC Letter, we are concurrently filing a pre-effective amendment to the Registration Statement pursuant
to Rule 472 under the Securities Act of 1933 incorporating disclosure changes in response to the comments
provided by the SEC in the SEC Letter.

PROSPECTUS

General

1. Comment: Please advise whether you have submitted or expect to submit
any exemptive applications or no-action requests in connection with your registration statement. The
Staff may have additional comments.

 Response: The
Trust has not submitted, and does not expect to submit, any exemptive applications or no-action requests
in connection with the Registration Statement.

Securities and
Exchange Commission

July 30, 2024

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2

2. Comment: Please provide the name of the Funds’ independent registered
public accounting firm in correspondence.

Response: The Trust’s Board of Trustees has appointed Ernst &
Young LLP as the independent registered public accounting firm of each Fund.

MFS Active
Core
Plus
Bond
ETF

Fees and Expenses, page 2

3. Comment: Please bold the second sentence of the Fee Table preamble
and move the third sentence to a footnote to “Other Expenses” as required by Item 3 of Form N-1A.
This comment applies to all of the Funds.

 Response: The
requested changes have been made for all Funds.

Principal Investment Strategies, page 3

4. Comment: Please add Principal Investment Strategies disclosure explaining
the significance of the term “Plus” in the Fund’s name. Please disclose any parameters the Fund
has with respect to the maturity or duration of its fixed income securities.

Response: The following disclosure
will be added to the “Principal Investment Strategies” disclosure in the Summary and Statutory sections
of the MFS Active Core Plus Bond ETF prospectus to explain the significance of the term “Plus” in
the Fund’s name.

“The fund’s investment strategy is
referred to as “Core Plus” because, in addition to investing in a core portfolio of investment grade
quality debt instruments, MFS normally invests a portion of the fund’s assets in below investment grade
quality debt instruments and/or emerging markets debt instruments.”

The
Fund does not have specific parameters for the maturity and/or duration of the debt instruments in which
it invests. As a result, no disclosure concerning maturity or duration parameters will be added to the
Fund’s Principal Investment Strategies disclosure.

5. Comment: With respect to the statement that the Fund may invest in
foreign securities, please disclose (1) any percentage limitations on foreign securities, (2) whether
foreign securities may include emerging market securities, and (3) if foreign securities do include emerging
market securities, please disclose how the Fund defines emerging markets. In this regard, we note that
you reference foreign investments tied economically to emerging markets in your Foreign Risk disclosure.
This comment applies to all of the Funds, other than the MFS Active International ETF.

 Response: Our
responses to each component of the above comment regarding the Funds’ disclosure relating to foreign
securities are set forth below.

Securities and
Exchange Commission

July 30, 2024

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(1.) With
respect to all of the Funds, there is no maximum percentage that the Fund may invest in foreign securities.
We believe the existing disclosure appropriately describes the Fund's principal strategies and the principal
risks of investing in the Fund; therefore, we respectfully decline to amend this disclosure.

(2.) Emerging
markets strategy and risk disclosure is included in a Fund’s prospectus if investing in emerging market
securities is a principal investment strategy of the Fund.  Currently, disclosure relating to investments
in emerging market securities is included in the prospectus for the MFS Active International ETF. In
addition, disclosure regarding investing in emerging markets as a principal investment strategy will
be added for the MFS Active Core Plus Bond ETF.

(3.) The following disclosure describing emerging markets will
be added for the MFS Active Core Plus Bond ETF and the MFS Active International ETF, each of which may
invest in emerging markets as a principal investment strategy:

Principal
Investment Strategies - Summary Section:

“Emerging markets
are countries determined to have emerging market economies based on factors that demonstrate the country's
financial and capital markets are in the development phase.”

Principal
Investment Strategies - Statutory Section:

“Emerging markets
are countries determined to have emerging market economies based on factors that demonstrate the country's
financial and capital markets are in the development phase.  Emerging markets include countries located
in Latin America, Asia, Africa, the Middle East, and developing countries of Europe, primarily Eastern
Europe.”

In addition, the Foreign Risk disclosure for MFS Active Growth
ETF and MFS Active Value ETF, which do not invest in emerging markets as a principal investment strategy,
will be revised as follows to remove the reference to emerging markets:

“Foreign
Risk:  Exposure to foreign markets through issuers or currencies can involve additional
risks relating to market, economic, industry, political, regulatory, geopolitical, environmental, public
health, and other conditions. These factors can make foreign investments, especially those
tied economically to emerging markets countries
with developing economies or
countries subject to sanctions or the threat of new or modified sanctions, more volatile and less liquid
than U.S. investments. In addition, foreign markets can react differently to these conditions than the
U.S. market.”

MFS Active Intermediate Muni ETF does
not include Foreign Risk disclosure in its prospectus.

6. Comment: With respect to your derivatives disclosure, please identify
the principal types of derivatives that the Fund intends to utilize, and tailor the disclosure specifically
to how each such

Securities and
Exchange Commission

July 30, 2024

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  instrument will be utilized in achieving the Fund’s objectives.
Also, provide appropriate risk disclosure associated with each derivative type. See Barry Miller Letter
to ICI (http://www.sec.gov/divisions/investment/guidance/ici073010.pdf). This comment applies to the
MFS Active Intermediate Muni Bond ETF, as well.

Response: We believe that the Fund's derivatives disclosure is consistent
with applicable SEC requirements and the guidance reflected in Barry Miller Letter to ICI dated July
10, 2010 (the "Derivatives Letter").  In particular, disclosure regarding the use of derivatives is only
included in the principal investment strategies disclosure for those Funds that are likely to use derivatives
as a principal investment strategy (i.e. the MFS Active Core Plus Bond ETF and the
MFS Active Intermediate Muni Bond ETF).  For those Funds that may use derivatives as a principal investment
strategy, the prospectus includes (i) the derivative types that may be utilized, with the derivative
type selected to implement an investment view at a given time varying based on factors such as current
cost and market conditions, as well as (ii) principal risk disclosure describing the principal risks
associated with such investments.  In addition, the derivatives disclosure references the investment
purposes for which the derivatives may be used, which is tailored to specific investment strategies within
the MFS Funds complex.

Principal Risks,
pages 3-4

7. Comment: Given your statement in the Principal Investment Strategies
section that debt instruments may include mortgage-backed and other asset-backed securities, please add
specific risk disclosure describing the risks of investing in these instruments.

Response: We believe the disclosure
in the Principal Risks sections of the Fund's Prospectus, including the Fund's Credit Risk and Prepayment/Extension
Risk disclosure, which include specific references to securitized instruments, adequately addresses the
risks associated with investing in mortgage-backed securities.  As a result, we do not believe it is
necessary to add separate risk disclosure specific to mortgage-based securities.  However, the Fund’s
Credit Risk disclosure will be revised as follows to clarify that the reference to securitized instruments
encompasses mortgage-backed securities.

“Credit
Risk:  The price of a debt instrument depends, in part, on the issuer's or borrower's
credit quality or ability to pay principal and interest when due. The price of a debt instrument is likely
to fall if an issuer or borrower defaults on its obligation to pay principal or interest, if the instrument's
credit rating is downgraded by a credit rating agency, or based on other changes in, or perceptions of,
the financial condition of the issuer or borrower.  For certain types of instruments, including derivatives,
the price of the instrument depends in part on the credit quality of the counterparty to the transaction.
For other types of debt instruments, including mortgage-backed securities
and other securitized instruments, the price of the debt instrument also depends on the
credit quality and adequacy of the underlying assets or collateral as well as whether there is a security
interest in the underlying assets or collateral. Enforcing rights, if any, against the underlying assets
or collateral may be difficult.”

Securities and
Exchange Commission

July 30, 2024

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8. Comment: We note that you have included “Focus Risk” as a principal
risk of investing in the Fund. If the Fund will have significant exposure to any industry, sector, country
or region, please add specific Principal Investment Strategies and Principal Risk disclosure describing
the industry, sector, country or region. This comment applies to all of the Funds.

Response: None of the Funds have
a principal investment strategy of focusing on a specific industry, sector, country, or region. We believe
that our current disclosure in the Principal Investment Strategies and Principal Risks sections of each
Fund's prospectus appropriately discloses the principal investment strategies and principal risks of
such Fund. However, industry, sector, country, or regional focus may occur as a result of the then-current
investment opportunities identified by a Fund's portfolio managers pursuant to the Fund's principal investment
strategies, rather than a principal investment strategy to focus the Fund's investments in any particular
industry, sector, country, or region.

9. Comment: Please
clarify in the filing why you state under Fluctuation of Net Asset Value and Share Price Risk that “[g]iven
the nature of the relevant markets for certain of the fund's securities, shares may trade at a larger
premium or discount to the NAV than shares of other ETFs.” This comment applies to all of the Funds.

 Response: The disclosure referenced above has been clarified as follows:

  “Given
the natureShares of the relevant markets for certain of
the fund's securities, sharesfund may trade at a larger premium or discount
to the NAV than shares of other ETFs that focus on other market segments or types of securities.”

10. Comment: Please confirm whether securities underlying the ETF are traded
outside of a collateralized settlement system. If so, please disclose that there are a limited number
of financial institutions that may act as authorized participants that post collateral for certain trades
on an agency basis (i.e., on behalf of other market participants). Please also disclose that, to the
extent that those authorized participants exit the business or are unable to process creation and/or
redemption orders and no other authorized participant is able to step forward to do so, there may be
a significantly diminished trading market for the ETF’s shares. In addition, please note that this
could in turn lead to differences between the market price of the ETF’s shares and the underlying value
of those shares. This comment applies to all of the Funds.

Response: The Trust confirms that the securities underlying
the ETFs will typically settle within a collateralized settlement system.  Additionally, we note that
each Fund’s prospectus includes the following disclosure in the “Principal Risks” section (emphasis
added):

“Authorized Participant Risk: Only
financial institutions authorized to transact daily with the fund (Authorized Participants) may engage
in creation or redemption transactions directly with the fund, and Authorized Participants are not obligated
to do so. The fund has a limited number of intermediaries that act as
Authorized Participants. There are no obligations of market makers to make a market
in the fund's shares or of Authorized Participants to submit creation or redemption orders for Creation
Units. Decisions by market makers and/or Authorized Participants to reduce their role with respect to
market making or creation and redemption activities during times of market stress, or a decline in the
number of Authorized Participants due to decisions to exit the business,

Securities and
Exchange Commission

July 30, 2024

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bankruptcy, or other factors, could inhibit
the effectiveness of the arbitrage process in maintaining the relationship between the underlying value
of the fund's portfolio securities and the market price of fund shares. To the
extent an Authorized Participant cannot or is otherwise unwilling to engage in creation and redemption
transactions, and no other Authorized Participant creates or redeems shares in such transactions, shares
of the fund may trade at a significant discount or premium to NAV and may face trading halts and/or delisting
from the exchange.”

Performance Information, page 4

11. Comment: Please supplementally identify the broad-based securities
market index expected to be used by the Fund in the average annual total returns table. This comment
applies to all of the Funds.

 Response: The
anticipated “appropriate broad-based securities market index” to be used for each Fund in the Average
Annual Total Returns table in the prospectus are provided in the table below. (Certain of the Funds may
also disclose an additional index in the prospectus that more closely reflects the market segments in
which the Fund invests.)

Fund

 Broad-Based Index

MFS Active Core Plus Bond ETF

 Bloomberg U.S. Aggregate Bond Index

MFS Active Growth ETF

 Russell 3000 Index

MFS Active Intermediate Muni Bond ETF

 Bloomberg Municipal
Bond Index

MFS Active International ETF

 MSCI All Country World Index (ACWI) ex-US Index

MFS A