Police were called at 4pm on Monday, 7 December to reports of a stabbing in Ridsdale Road, SE20.
The man is understood to have been stabbed and collapsed on Platform one of Anerley station. Officers from BTP and the Met gave the made treatment before the arrival of the LAS.
A spokesman for the Met Police Said:
Officers and London Ambulance Service attended. A man his 20s has been taken to a south London hospital. We await an update on his condition.
At this early stage, there have been no arrests.
A crime scene remains in place and enquiries continue.