Five teenagers attacked a Brighton man in the Hanover area of town at the weekend.
The victim, 26, was left with a broken cheek bone and nerve damage to his face.
He was taken to the Royal Sussex County Hospital in Eastern Road, Brighton, for treatment where doctors had to insert a metal plate in his cheek.
The man was walking home from a night out when he came across the youths and asked for a cigarette.
They attacked him, punching him several times on the side of the head.
Detective Constable Caroline Biggs said: “This was a very nasty attack on an innocent young man walking home from a night out in Brighton.
“It has left the victim with both emotional and physical scars.
“I would appeal to anyone who witnessed the attack to please contact us.”
The unprovoked attack happened in the early hours of Saturday morning in Elm Grove, Brighton.
The five male suspects are all thought to be around 15 to 17 years old.
Anyone who saw the assault is asked to contact Sussex Police on 0845 6070999 or the independent charity Crimestoppers anonymously on 0800 555111.
