A man suffered a broken arm in an attack outside a nightclub in Sheffield city centre as he was trying to get into a taxi.
The 20-year-old was also repeatedly punched in the attack outside Corporation in Milton Street at around 2am on Saturday, June 11.
A South Yorkshire Police spokeswoman said: "It is understood that the 20-year-old was waiting to get into a taxi when the suspect approached and repeatedly punched him.
"The victim required hospital treatment for facial injuries and a broken arm.
"Despite enquiries in the local area and examination of CCTV, no arrests have been made and no suspects identified."
The suspect was black and in his early twenties.
Anyone with information should call South Yorkshire Police on 101.