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The reader should not assume that the information is accurate and complete.

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 13F

FORM 13F COVER PAGE
OMB APPROVAL
OMB Number: 3235-0006
Estimated average burden
hours per response: 23.8
Report for the Calendar Year or Quarter Ended: 03-31-2023
Check here if Amendment    Amendment Number:
This Amendment (Check only one.):    is a restatement.
   adds new holdings entries.
Institutional Investment Manager Filing this Report:
Name: Bain Capital Life Sciences Investors, LLC
Address: 200 Clarendon Street
Boston, MA  02116
Form 13F File Number: 028-18477
CRD Number (if applicable):
SEC File Number (if applicable):

The institutional investment manager filing this report and the person by whom it is signed hereby represent that the person signing the report is authorized to submit it, that all information contained herein is true, correct and complete, and that it is understood that all required items, statements, schedules, lists, and tables, are considered integral parts of this form.

Person Signing this Report on Behalf of Reporting Manager:
Name: Adam Koppel
Title: Partner of Bain Capital Life Sciences Investors, LLC
Phone: 617-516-2000
Signature, Place, and Date of Signing:
/s/ Adam Koppel Boston,  MA 05-15-2023
[Signature] [City, State] [Date]
Bain Capital Life Sciences Investors, LLC is (i) the general partner of Bain Capital Life Sciences Partners, LP, which is the general partner of Bain Capital Life Sciences Fund, L.P., (ii) the general partner of BC SW, LP, (iii) the manager of Bain Capital Life Sciences Investors II, LLC, which is the general partner of Bain Capital Life Sciences Fund II, L.P., which is the manager of BCLS II Investco (GP), LLC, which is the general partner of BCLS II Investco, LP, and (iv) the manager of Bain Capital Life Sciences III General Partner, LLC, which is the general partner of Bain Capital Life Sciences Fund III, L.P., which is the sole member of Bain Capital Life Sciences Opportunities III GP, LLC, which is the general partner of Bain Capital Life Sciences Opportunities III, LP. The shares of Annexon, Inc. ("ANNX") are as reported on Amendment No. 1 to the Schedule 13G filed by Bain Capital Life Sciences Fund, L.P., BCIP Life Sciences Associates, LP and BCLS I Investco, LP on 2/14/23 and reflect the exercise of securities held by such persons for ANNX common stock, after giving effect to provisions that prevent exercise if such persons would beneficially own more than 9.99% of the ANNX common stock following such exercise. As of 3/31/23, such persons held 3,601,926 shares of ANNX common stock. The shares of Disc Medicine, Inc. ("IRON") are as reported on the Schedule 13G filed by Bain Capital Life Sciences Opportunities III, LP on 2/24/23 and reflect the exercise of securities held by such person for IRON common stock, after giving effect to provisions that prevent exercise if such person would beneficially own more than 9.99% of the IRON common stock following such exercise. As of 3/31/23, such person held 944,687 shares of IRON common stock. The shares of Savara Inc. ("SVRA") are as reported on Amendment No. 1 to the Schedule 13D filed by Bain Capital Life Sciences Fund II, L.P. and BCIP Life Sciences Associates, LP on 3/17/21 and reflect the exercise of securities held by such persons for SVRA common stock, after giving effect to provisions that prevent exercise if such persons would beneficially own more than 9.99% of the SVRA common stock following such exercise. As of 3/31/23, such persons held 6,913,208 shares of SVRA common stock. The shares of Syros Pharmaceuticals, Inc. ("SYRS") are as reported on Amendment No. 2 to the Schedule 13G filed by Bain Capital Life Sciences Fund II, L.P., BCIP Life Sciences Associates, LP and BCLS II Equity Opportunities, LP on 2/14/23 and reflect the exercise of securities held by such persons for SYRS common stock, after giving effect to provisions that prevent exercise if such persons would beneficially own more than 9.99% of the SYRS common stock following such exercise. As of 3/31/23, such persons held 1,082,404 shares of SYRS common stock. The shares of X4 Pharmaceuticals, Inc. ("XFOR") are as reported on Amendment No. 2 to the Schedule 13G filed by Bain Capital Life Sciences Fund, L.P., Bain Capital Life Sciences Fund II, L.P., BCIP Life Sciences Associates, LP, BCLS II Investco, LP and BCLS I Investco, LP on 2/14/23 and reflect the exercise of securities held by such persons for XFOR common stock, after giving effect to provisions that prevent exercise if such persons would beneficially own more than 9.99% of the XFOR common stock following such exercise. As of 3/31/23, such persons held 11,590,336 shares of XFOR common stock.
Report Type (Check only one.):
X 13F HOLDINGS REPORT. (Check here if all holdings of this reporting manager are reported in this report.)
   13F NOTICE. (Check here if no holdings reported are in this report, and all holdings are reported by other reporting manager(s).)
   13F COMBINATION REPORT. (Check here if a portion of the holdings for this reporting manager are reported in this report and a portion are reported by other reporting manager(s).)
Form 13F Summary Page
Report Summary:
Number of Other Included Managers: 11
Form 13F Information Table Entry Total: 34
Form 13F Information Table Value Total: 800,117
(round to nearest dollar)
List of Other Included Managers:
Provide a numbered list of the name(s) and Form 13F file number(s) of all institutional investment managers with respect to which this report is filed, other than the manager filing this report.
[If there are no entries in this list, state “NONE” and omit the column headings and list entries.]
No. Name Form 13F File No. CRD No. (if applicable) SEC File No. (if applicable) CIK
1 Bain Capital Life Sciences Partners, LP 28-18476      
2 Bain Capital Life Sciences Fund, L.P. 28-18478      
3 BC SW, LP 28-20270      
4 Bain Capital Life Sciences Investors II, LLC 28-20816      
5 Bain Capital Life Sciences Fund II, L.P. 28-20814      
6 BCLS II Investco (GP), LLC 28-22976      
7 BCLS II Investco, LP 28-22978      
8 Bain Capital Life Sciences III General Partner, LLC 28-22975      
9 Bain Capital Life Sciences Fund III, L.P. 28-22979      
10 Bain Capital Life Sciences Opportunities III GP, LLC 28-22968      
11 Bain Capital Life Sciences Opportunities III, LP 28-22966