Police want people to be careful late at night during the party season.
Detective Senior Sergeant Darrell Harpur of the Ormiston CIB says there is usually a seasonal increase in public violence "and that is being borne out by what we are experiencing at the moment".
"We've had a couple of serious assaults of late, and they are both Howick parties, and both victims have sustained really quite serious injuries," he says.
"There was one on Bleakhouse Rd a couple of months ago and he sustained serious head injuries, and there was one recently in Howick and he got a broken jaw.
"So we just want people to be vigilant, don't drink too much and look after your friends and mates."
Party hosts can ring police on 362 1130 to advise of plans and supply a contact number in case revelry gets out of hand.