A 47-year-old Hove man suffered a serious head injury after being attacked outside a pub.
The man needed 13 staples to close a 6in cut to his head. He was also left with a swollen left eye and jaw.
The attack took place outside the Albion pub in Church Road, Hove, at about 7pm on Sunday 29 January.
The victim was taken to the Royal Sussex County Hospital in Brighton for treatment.
PC Paul Baker said: “We are trying to establish the circumstances that led up to this horrible attack.
“I would particularly like to appeal to people who were standing at a nearby bus stop outside the pub and would have witnessed the assault.
“Also, any members of the public who were going about their daily business and may have seen any suspicious activity.”