Bain Capital Life Sciences Investors 13FHR Quarterly holdings report by institutional manager

The Securities and Exchange Commission has not necessarily reviewed the information in this filing and has not determined if it is accurate and complete.
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

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Report for the Calendar Year or Quarter Ended:

12-31-2022

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

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	02-14-2023
[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 parter 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 parnter 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 common stock of Annexon, Inc. ("ANNX") included on the Information Table 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 February 14, 2023 and reflect the exercise of securities exercisable for shares of ANNX common stock held by such persons, after giving effect to the provisions of such securities that prevent the exercise of such securities if such persons would beneficially own more than 9.99% of the outstanding ANNX common stock following such exercise. As of December 31, 2022, such persons held an aggregate of 3,601,926 shares of ANNX common stock. The shares of common stock of Savara Inc. ("SVRA") included on the Information Table 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 March 17, 2021 and reflect the exercise of securities exercisable for shares of SVRA common stock held by such persons, after giving effect to the provisions of such securities that prevent the exercise of such securities if such persons would beneficially own more than 9.99% of the outstanding SVRA common stock following such exercise. As of December 31, 2022, such persons held an aggregate of 6,913,208 shares of SVRA common stock. The shares of common stock of Syros Pharmaceuticals, Inc. ("SYRS") included on the Information Table 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 February 14, 2023 and reflect the exercise of securities exercisable for shares of SYRS common stock held by such persons, after giving effect to the provisions of such securities that prevent the exercise of such securities if such persons would beneficially own more than 9.99% of the outstanding SYRS common stock following such exercise. As of December 31, 2022, such persons held an aggregate of 1,082,404 shares of SYRS common stock. The shares of common stock of X4 Pharmaceuticals, Inc. ("XFOR") included on the Information Table 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 February 14, 2023 and reflect the exercise of securities exercisable for shares of XFOR common stock held by such persons, after giving effect to the provisions of such securities that prevent the exercise of such securities if such persons would beneficially own more than 9.99% of the outstanding XFOR common stock following such exercise. As of December 31, 2022, such persons held an aggregate of 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:	33
	Form 13F Information Table Value Total:	894,849
		(thousands)

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.	Form 13F File Number	Name
	1	28-18476	Bain Capital Life Sciences Partners, LP
	2	28-18478	Bain Capital Life Sciences Fund, L.P.
	3	28-20270	BC SW, LP
	4	28-20816	Bain Capital Life Sciences Investors II, LLC
	5	28-20814	Bain Capital Life Sciences Fund II, L.P.
	6		BCLS II Investco (GP), LLC
	7		BCLS II Investco, LP
	8		Bain Capital Life Sciences III General Partner, LLC
	9		Bain Capital Life Sciences Fund III, L.P.
	10		Bain Capital Life Sciences Opportunities III GP, LLC
	11		Bain Capital Life Sciences Opportunities III, LP

Bain Capital Life Sciences Investors 13F-HRQuarterly holdings report by institutional manager