The man was on the roof of a Castle St property taking pictures with some friends when he lost his balance, slid down the roof and fell, Sergeant Matt Lee, of Dunedin, said.
He struck his head when landing on the pavement.
Emergency services were called to the address at the corner of Castle St and Dundas St at 10.10pm.
The teenager was transported to Dunedin Hospital in a critical condition by Hato Hone St John.
There was a small gathering at the property at the time.
Inquiries were ongoing into the incident.
A University of Otago spokeswoman said their thoughts were with the student and his whānau.
‘‘University staff are supporting the student, his whānau and fellow students to ensure they have the care and assistance they need.’’
She said out of respect for the teenager, the university would not provide any further information.
