A man was slashed with a knife along his torso during an evening out with friends.
The 22-year-old man was in Trafalgar Street, Brighton, near to the Trafalgar Court junctio, when he was assaulted.
Police are appealing for witnesses to the incident which took place around 8pm.
Detective Constable Duncan Lloyd said: "A woman was arrested at the time of the incident, however we would like to speak to anyone who witnessed the incident and can give us some details of what happened."
A 33-year-old woman from Brighton, was arrested on suspicion of assault. She was questioned and released on bail until September 7.
Any witness or anyone with information about the incident is asked to email firstname.lastname@example.org or call 101 quoting serial 1479 of 02/08. Alternatively, call the independent charity Crimestoppers anonymously on 0800 555 111.