SecProbe.io

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                             Bell, Boyd & Lloyd LLC
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       70 West Madison Street, Suite 3100 - Chicago, Illinois 60602-4207
                        312.372.1121 - Fax 312.827.8000

VIA EDGAR

                                 April 25, 2005

Ms. Alison T. White
Securities and Exchange Commission
Division of Investment Management
450 Fifth Street, N.W.
Washington, DC  20549

                             CALAMOS ADVISORS TRUST

Dear Ms. White:

     This letter responds to the comments you conveyed via e-mail on April 11,
2005, on the post-effective amendment to the registration statement filed on
behalf of Calamos Advisors Trust (the "Trust") on form N-1A regarding the
Calamos Growth and Income Portfolio (the "Fund"). For convenience, each of your
comments is repeated below, with responses immediately following. Where revised
disclosure from the post-effective amendment is included in a response, we have
marked the disclosure to show changes from the original post-effective amendment
filing on March 1, 2005. Those pages of the revised post-effective amendment
that reflect the changes made in response to your comments are attached, and the
changes are marked with the number of the comment to which the particular
revision relates. We are hoping to file a post-effective amendment to the
Trust's registration statement on or before April 28, 2005, so we hope to
resolve any outstanding issues as quickly as possible.

PROSPECTUS

1.   BACK COVER PAGE

          COMMENT: a. Please clarify whether the Fund makes available its SAI
          and annual and semi-annual reports, free of charge on or through the
          Fund's web site. If the Fund does not make its SAI and shareholder
          reports available in this manner, disclose the reasons why it does not
          do so. See Item 1(b)(1) of Form N1-A.

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                              chicago - washington

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Ms. Alison White
April 25, 2005
Page 2

          RESPONSE: The Fund does not make available its SAI and annual and
          semi-annual reports on its website. We will revise the third paragraph
          under the heading "Statement of Additional Information" on the back
          cover of the prospectus to read in its entirety as follows:

               "You can get more information on Calamos Advisors LLC on its
          internet website at http://www.calamos.com. Because the Portfolio is
          sold exclusively as an underlying investment vehicle for insurance
          products purchased by clients of KC Life, the Portfolio's SAI and
          annual and semi-annual reports are not available on Calamos Advisors'
          website."

          COMMENT: b. Please disclose that the Public Reference Room's zip code
          is 20549-0102. See Item 1(b)(3) of Form N-1A.

          RESPONSE: We will make the requested revision.

2.   SHAREHOLDER FEES (FEES PAID DIRECTLY FROM YOUR INVESTMENT), PAGE 9

          COMMENT: If there are no shareholder fees, please indicate they are
          N/A or delete the section altogether. See Instruction (1)(c) to Item 3
          of Form N1-A.

          RESPONSE: At the end of each of the four line items under the heading
          "Shareholder Fees (Fees Paid Directly from Your Investment)", we will
          insert the word "None".

3.   EXCESSIVE TRADING, PAGE 11

          COMMENT: a. If the Fund's board of directors has not adopted policies
          and procedures with respect to frequent purchases and redemptions,
          please provide a statement of the specific basis for the view of the
          board that it is appropriate for the Fund not to have such policies
          and procedures in place. Note that the fact that the Fund has a
          "single shareholder" does not eliminate the risk of market timing when
          the single shareholder is an insurance company omnibus account.

          b.   If the Fund relies solely on insurance companies to impose
          market-timing restrictions, disclose the risks of this policy, and
          describe the difficulty in detecting market-timing because of the
          omnibus account structure. Disclose whether the Fund takes any actions
          to assure that the insurance companies have effective-market timing
          procedures in place.

          c.   Disclose whether the Fund discourages or accommodates
          market-timing.

          RESPONSE: In response to all three comments above, on pages 11 and 12
          of the prospectus, we will replace the three paragraphs under the
          heading "Excessive Trading" with the following three paragraphs:

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Ms. Alison White
April 25, 2005
Page 3

               "The Portfolio seeks to discourage abusive trading, which may
          include frequent trading or short-term trading. Abusive trading may
          interfere with the efficient management of the Portfolio, and may
          result in the Portfolio maintaining higher cash balances, utilizing a
          line of credit and engaging in additional Portfolio transactions.
          Increased Portfolio transactions and utilization of a line of credit
          would increase the Portfolio's operating costs and decrease its
          investment performance. Maintenance of high cash balances would result
          in lower Portfolio investment performance during periods of rising
          markets.

               Because of the potentially harmful effects of abusive trading,
          the trustees of the Portfolio have approved fair valuation pricing
          procedures to reduce the arbitrage opportunities in the Portfolio. The
          Portfolio has not implemented redemption fees or transfer limits in
          reliance on the abusive trading policies and procedures implemented
          and maintained by the sole shareholder of the Portfolio.

               The Portfolio is sold exclusively as an underlying investment
          vehicle for insurance products purchased by clients of the Kansas City
          Life Insurance Company ("KC Life"). The Portfolio is typically unable
          to identify clients of KC Life that are engaging in abusive trading
          practices because KC Life has the exclusive relationship with, and
          maintains the account records of, the clients directing trading
          activity in the Portfolio. As a result, the Portfolio's ability to
          monitor and discourage abusive trading practices is limited. The
          Portfolio monitors aggregate trades placed by KC Life separate
          accounts. So as to combat abusive trading, KC Life imposes surrender
          charges, transfer processing fees and currently monitors for twelve or
          more transfers within a calendar year. If inappropriate trading by a
          KC Life client is detected, the Portfolio may request that KC Life
          take action to prevent the particular client from engaging in that
          trading. Please refer to your KC Life contract for details about
          whether and how restrictions or limitations on trading activity may be
          applied to your account. Please refer to your KC Life product
          prospectus for more information about how trading activity is
          monitored."

4.   DISTRIBUTION ARRANGEMENTS

          COMMENT: If the Fund has adopted a plan under Rule 12b-1, please
          provide the information required by Items 7(b) and 14(g) of Form N-1A.

          RESPONSE: The Fund has not adopted a plan under Rule 12b-1. On page 9
          of the Prospectus, the second line under the heading "Annual Portfolio
          Operating

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Ms. Alison White
April 25, 2005
Page 4

          Expenses (Expenses that are Deducted from Portfolio Assets)" will read
          as follows:

          "Distribution (12b-1) and/or Service Fees . . . . .  . . . . . . None"

5.   DISCLOSURE OF PORTFOLIO HOLDINGS, SAI PAGE 25

          COMMENT: Please identify the individuals or categories of individuals
          who may authorized disclosure of portfolio holdings.

          RESPONSE: We will add to the SAI the following sentence at the end of
          the sixth paragraph under the heading "Disclosure of Portfolio
          Holdings":

          "Any such disclosure must be approved in writing by an officer of the
          Trust, after consultation with Calamos Advisors' Legal/Compliance
          Department."

6.   PORTFOLIO MANAGERS, SAI PAGE 29

          COMMENT: Please provide more detail as to the criteria for
          determining: (1) the annual discretionary target bonus, (2) the
          maximum annual bonus, (3) the amounts due under the annual long-term
          performance incentive plan and (4) the annual equity awards under the
          Incentive Compensation Plan. See Item 15(b) of Form N1-A.

          RESPONSE: On page 29 of the SAI, we will revise the fifth paragraph,
          and add a new sixth paragraph, under the heading "Portfolio Managers"
          as follows:

               "As of December 31, 2004, the portfolio managers receive all of
          their compensation from Calamos Asset Management, Inc. The portfolio
          managers have each entered into employment agreements that provide for
          compensation in the form of a minimum annual base salary and a maximum
          annual discretionary target bonus. The amounts paid to portfolio
          managers and the criteria utilized to determine the amounts are
          benchmarked against industry specific data provided by third party
          analytical agencies. The discretionary target bonus is set at a
          percentage of base salary, ranging from 500% to 600% of base salary,
          with a maximum annual bonus opportunity of at least 150% of the target
          bonus. Portfolio performance, as measured by risk-adjusted portfolio
          performance, is utilized to determine the discretionary target bonus.
          Also, due to the portfolio managers' ownership and executive
          management positions with Calamos Advisors and its parent company,
          additional multiple corporate objectives are utilized to determine the
          discretionary target bonus. For 2004, the additional corporate
          objectives

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Ms. Alison White
April 25, 2005
Page 5

          were advisory fee revenue, measured by growth in revenues compared to
          industry percentages; marketing effectiveness, as measured by growth
          in assets under management relative to industry percentages; operating
          efficiencies, as measured by operating margin relative to industry
          levels; and stock price performance.

               The portfolio managers are also eligible to receive annual equity
          awards under a long term incentive compensation program. The target
          annual equity awards are set at a percentage of base salary, ranging
          from 250% to 300%.

7.   DISTRIBUTOR, SAI PAGE 31

     COMMENT: Disclose whether the offering is continuous. See Item 20(a)(2) of
     Form N-1A.

     RESPONSE: On page 31 of the SAI, we will revise the penultimate sentence of
     the paragraph under the heading "Distributor" to read as follows:

     "CFS has the exclusive right to distribute shares of the Portfolio and the
     shares are offered on a continuous basis."

8.   OTHER

     COMMENT: We urge all persons who are responsible for the accuracy and
     adequacy of the disclosure in the filings reviewed by the staff to be
     certain that they have provided all information investors require. Since
     the fund and its management are in possession of all facts relating to the
     fund's disclosure, they are responsible for the accuracy and adequacy of
     the disclosures they have made.

     RESPONSE: We have been informed by the Fund and its management that they
     acknowledge and have read this comment.

                                    * * * * *

          We believe that this information responds to all of your comments. In
     addition, the Fund will file via EDGAR the "Tandy Letter" representations
     requested in your comments of April 11, 2005. Please call me to confirm the
     adequacy of our responses at 312/807-4341.

                                                     Very truly yours,

                                                     /s/ Kevin J. McCarthy
                                                     ---------------------
                                                     Kevin J. McCarthy

KJM:aap
Enclosures

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                        [Calamos Investments Letterhead]

                                 April 21, 2005

BY EDGAR

Securities and Exchange Commission
450 Fifth Street, N.W.
Washington, DC  20549

Ladies and Gentlemen:

                             Calamos Advisors Trust
                       1933 Act Registration No. 333-72511
                       1940 Act Registration No. 811-09237

     On behalf of the Calamos Advisors Trust (the "Trust"), we hereby make the
following representations:

     (i) The Trust is responsible for the adequacy and accuracy of the
disclosure in its filings with the Securities and Exchange Commission (the
"Commission");

     (ii) Staff comments or changes to disclosure in response to staff comments
in the filings reviewed by the staff do not foreclose the Commission from taking
any action with respect to the Trust's filings; and

     (iii) The Trust acknowledges that it may not assert staff comments as a
defense in any proceeding initiated by the Commission or any person under the
federal securities laws of the United States.

                                            CALAMOS ADVISORS TRUST

                                            By:  /s/ James S. Hamman, Jr.
                                                 ------------------------
                                            Name:  James S. Hamman, Jr.
                                            Title: Secretary

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