Company: EVF
Filing Date: 2025-06-12
Form Type: 424B3
Source: 0001076598-25-000219
Chunk: 0

Company: Eaton Vance Senior Income Trust
Filing Date: 2025-06-12
Form: 424B3
Chunk 0
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| Filed pursuant to Rule 424(b)(3) 
 File No. 333-263033              |

<div align='center'>EATON VANCE SENIOR INCOME TRUST

Supplement to Prospectus and Statement of Additional Information dated August 25, 2022

as may be supplemented and/or revised from time to time</div>

1.The following replaces the fifth paragraph under “The Adviser” in “Management of the Trust” in the Trust’s Prospectus:

Peter Campo, Catherine C. McDermott and Daniel P. McElaney are the
portfolio managers of the Trust. Mr. Campo and Ms. McDermott are Managing Directors of Morgan Stanley and Vice Presidents of Eaton
Vance. Mr. McElaney is an Executive Director of Morgan Stanley and a Vice President of Eaton Vance. Ms. McDermott and Mr. McElaney
have managed the Trust since March 2019, and Mr. Campo has managed the Trust since June 12, 2025. Ms. McDermott and Mr. McElaney
have been employees of the Morgan Stanley organization for more than five years and manage other Eaton Vance funds. Mr. Campo has
been an employee of the Morgan Stanley organization since April 2025 and manages other Eaton Vance funds. Prior to joining Morgan
Stanley, Mr. Campo worked at Goldman Sachs as Global Co-Head of High Yield & Bank Loan Credit since March 2018. Prior to joining
Goldman Sachs, Mr. Campo served for more than 15 years as a Portfolio Manager and senior credit analyst on the Floating-Rate Loan
team at Eaton Vance.

2. The following replaces the tables under “Portfolio Managers.” in “Investment Advisory and Other Services” in the Trust’s SAI:

|                                    |    Number of 
 All Accounts | Total Assets of 
    All Accounts |       Number of Accounts 
 Paying a Performance Fee | Total Assets of Accounts 
 Paying a Performance Fee |
| Peter Campo(1)                     |              |                 |                          |                          |
| Registered Investment Companies(2) |            0 |              $0 |                        0 |                       $0 |
| Other Pooled Investment Vehicles   |            0 |              $0 |                        0 |                       $0 |
| Other Accounts                     |            0 |              $0 |                        0 |                       $0 |
| Catherine C. McDermott             |              |                 |                          |                          |
| Registered Investment Companies(2)