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Faegre Drinker Biddle & Reath LLP

320 South Canal Street, Suite 3300

Chicago, IL 60606

(312) 569-1000 (Phone)

(312) 569-3000 (Facsimile)

www.faegredrinker.com

November 3, 2022

VIA EDGAR TRANSMISSION

U.S. Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549

Attention: Lauren Hamilton

  Re: RiverNorth Managed Duration Municipal Income Fund, Inc. (the “Fund” or the “Registrant”) (File Nos. 333-260490; 811-23434);

                                                                                Response to Examiner Comments on N-2

Dear Ms. Hamilton:

This letter responds
to the staff’s comments that you provided via telephone on October 25, 2022, in connection with your review of the Fund’s
above-referenced registration statement (“Registration Statement”) on Form N-2.

For your convenience,
we have repeated each comment below in bold, and our responses follow your comments. Capitalized terms not otherwise defined herein shall
have the meaning ascribed to them in the Registration Statement, unless otherwise indicated.

ACCOUNTING

 1. In the fee table, please supplementally explain how the weighted average annual expense to the Fund
is 0.92% and the leverage costs item listed in the fee table is 0.55%.

The leverage expense ratio of 0.55% within
the fee table is calculated by taking the total leverage expense from the fiscal year ended June 30, 2022, of $2,072,010, divided by the
average net assets for the same period. The weighted average interest rate paid on the leverage is 0.92%, calculated by taking the average
interest rate of the tender option bonds (“TOBs”) multiplied by the average TOB balance, plus the average interest rate on
the line of credit (“LOC”) multiplied by the average LOC balance, all divided by the sum of the average TOB balance plus the
average LOC balance for the year ended June 30, 2022 [((0.91%*214,563,751) + (1.13%*10,273,973)) / (214,563,751+10,273,973)].

 2. Please supplementally explain why the asset coverage with respect to borrowings under the Pershing
Facility and from tender option bond transactions in the Effects of Leverage paragraph on page 32 differs from the asset coverage ratios
for the line of credit and floating rate obligations payable in the June 30, 2022 financial highlights. For example, the Effects of Leverage
paragraph notes that asset coverage with respect to borrowings under the Pershing Facility was 5,575% and from tender option bond transactions
was 249% and the financial highlights lists 33,406 for asset coverage per $1,000 of line of credit and 2,452 for asset coverage per $1,000
of floating rate obligations payable.

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The Registrant confirms that the rates in the
Effects of Leverage paragraph should state “Asset coverage with respect to borrowings under the Pershing Facility was 3,341% and
from tender option bond transactions was 245%.” and will be updated in the appropriate supplement filing.

We trust that the
foregoing is responsive to your comments. Questions and comments concerning this filing may be directed to the undersigned at (312) 569-1107.

    Sincerely,

    /s/ David L. Williams

    David L. Williams

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