Officers were called to Gladstone Street near Manchester Road in Swindon at approximately 11.30pm on Friday night (05/07).
A man in his 20s had been found with a slash type injury to his head and minor injuries to his leg and hand.
His conditions is not described as life threatening. The ambulance service attended and he was taken to hospital for further treatment.
A spokesperson for Wiltshire Police said: "We would urge anyone who witnessed any suspicious activity in the area to call police immediately.
"We are particularly interested in hearing from anyone who saw a man described as black, aged between 25 and 35, tall and of an athletic build, with hair down to his shoulders in the area around this time."
Officers conducted an area search and a cordon was put in place while further enquiries were carried out – this was lifted just before 3am and our enquiries are ongoing.
Anyone with information should call 101 and quote crime reference number 54190065522.
Alternatively, call Crimestoppers anonymously on 0800 555 111.