Police were called to an injured man in Leyton High Road at around 7.25am on Sunday, 19 May.
Officers attended along with ambulance colleagues.
The man has been taken to hospital suffering head injuries. Police await an assessment of his condition.
Officers believe he had been assaulted. There has been no arrest. Enquiries continue.
Anyone with information that may assist police is asked to call 101, ref 1710/18may.