The man suffered a nasty cut to his head in the incident which took place in Leicester Street, Walsall, in the early hours of Saturday morning.
The 25-year-old man was involved in an altercation with three men and feel backwards, hitting his head on the ground, after being punched by one of them.
Officers from West Midlands Police and an ambulance from West Midlands Ambulance Service attended the scene and treated the man for his injuries, before taking him to hospital.
A spokesman for West Midlands Police said: "We're investigating after a man was assaulted on a night out in Walsall over the weekend.
"The 25-year-old was involved in an altercation with three men just after 12.20am on Saturday.
"One of them punched him and he fell backwards and hit his head on the ground.
"He sustained a nasty cut and was taken to hospital for treatment.
"The incident happened on Leicester Street.
"We’re looking into it and anyone with information about what happened should contact us as soon as possible."
Nobody has been arrested over the violence.
A spokeswoman for West Midlands Ambulance Service said: "We were called at 0.16am on Saturday to Leicester Street, Walsall to reports of an assault.
"One ambulance attended and treated a man on scene for injuries before he was taken to hospital for further care."
Anyone with information is asked to contact police or Crimestoppers quoting investigation number 20/1746576/21.