Detectives are investigating an unexplained death outside Greenford Station.
Police were called to Oldfield Lane North at 01:46hrs on Saturday, 23 June following reports of a fight.
Officers and the London Ambulance Service attended and found two unresponsive men aged in their late 30s.
The first man was pronounced dead at the scene.
A post-mortem examination will be held in due course and formal identification awaits.
Police are in the process of informing his next-of-kin.
The second man has been taken to hospital with a suspected head injury. He remains in a stable condition.
Enquiries into the full circumstances of the incident continue.
A crime scene remains in place. Greenford Station is in the process of being reopened.
Anyone with information is requested to call police via 101 quoting reference 612/23June. You can also tweet information to police via @MetCC
No arrests have been made and enquiries continue.