Initial Statement of Beneficial Ownership (3)

FORM 3	UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES	OMB APPROVAL OMB Number: 3235-0104 Estimated average burden hours per response... 0.5
	Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person * MORGAN STANLEY	2. Date of Event Requiring Statement (MM/DD/YYYY) 3/1/2021	3. Issuer Name and Ticker or Trading Symbol EATON VANCE SENIOR INCOME TRUST [EVF]
(Last)        (First)        (Middle) 1585 BROADWAY	4. Relationship of Reporting Person(s) to Issuer (Check all applicable) _____ Director                          _____ 10% Owner _____ Officer (give title below)        ___X___ Other (specify below) / Investment adviser affiliate
(Street) NEW YORK, NY 10036       (City)              (State)              (Zip)	5. If Amendment, Date Original Filed(MM/DD/YYYY)	6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Auction Preferred Stock	94	I	By Subsidiary

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivate Security (Instr. 4)	2. Date Exercisable and Expiration Date (MM/DD/YYYY)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

Remarks: The preferred shares reported herein represent the Reporting Person's combined holdings in multiple series of auction preferred securities of the Issuer, which are treated herein as one class of securities in accordance with the Auction Rate Securities - Global Exemptive Relief no-action letter issued by the Securities and Exchange Commission (the "SEC") on September 22, 2008 (the "Letter"). The Reporting Person undertakes to provide, upon request by the SEC staff, the Issuer, or a security holder of the Issuer, complete information regarding the number of such preferred shares purchased and sold for cash at par (plus dividends, if any) at each different date after the date hereof and not reported on Form 4 in accordance with the Letter. The reporting person is an affiliate of the Issuer's investment adviser.

Reporting Owners
Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MORGAN STANLEY 1585 BROADWAY NEW YORK, NY 10036				Investment adviser affiliate

Signatures
/s/ Joseph Maehr		3/11/2021
**Signature of Reporting Person		Date