The victim was set upon by the group, including one person carrying a machete or similar weapon, in a car park in front of public toilets across from Queens Gardens in the city centre about 1am.
He had surgery yesterday for serious facial and head injuries, which were not life-threatening.
Detective Sergeant Rob Hanna, of the Dunedin CIB, said the man remained in Dunedin Hospital yesterday and was yet to be interviewed by police.
He said officers' initial inquiries were starting to give them a clearer picture of what happened, but they still had several people to interview.
Those involved included people from Dunedin and from Balclutha. After the attack, the group had left the scene in four vehicles.
Several people visited the Dunedin Central police station yesterday about the attack and police were still keen to hear from anyone with information, Det Sgt Hanna said.
