Cover Page - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Sep. 13, 2024	Dec. 31, 2023
Document Information [Line Items]
Document Type	10-K
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	FY
Securities Act File Number	000-50484
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	51-0407811
Entity Address, Address Line One	9920 Pacific Heights Blvd
Entity Address, Address Line Two	Suite 150
Entity Address, City or Town	San Diego
Entity Address, Postal Zip Code	92121
City Area Code	858
Local Phone Number	369-7100
Trading Symbol	MEIP
Entity Registrant Name	MEI Pharma, Inc.
Entity Central Index Key	0001262104
Current Fiscal Year End Date	--06-30
Entity Filer Category	Non-accelerated Filer
Entity Current Reporting Status	Yes
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Small Business	true
Title of 12(b) Security	Common Stock, $0.00000002 par value
Security Exchange Name	NASDAQ
Entity Interactive Data Current	Yes
Entity Address, State or Province	CA
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
ICFR Auditor Attestation Flag	false
Entity Common Stock, Shares Outstanding			6,662,857
Entity Public Float				$ 28.7
Auditor Firm ID	34	243
Auditor Location	San Diego, California	San Diego, California
Auditor Name	Deloitte and Touche LLP	BDO USA, P.C
Document Financial Statement Error Correction [Flag]	false