The man was attacked in Bangor’s High Street around 1.40 am, say police.
He was taken to the accident and emergency department at the Ulster Hospital in Dundonald for treatment.
Officers are studying CCTV footage in an effort to identify the attackers.
Detective Sergeant James Johnston from Bangor’s Reactive and Organised Crime Branch is appealing for anyone who witnessed the assault or has information that can help the investigation to contact detectives on 101 non-emergency number.
Alternatively, information can also be passed anonymously to Crimestoppers on 0800 555 111.