A teenager has died in hospital from head injuries after attending a party at Girrawheen late on Friday.

Police said 17-year-old Kuol Akut, from Ballajura, died in Royal Perth Hospital just before midday.

He had been in a coma since the party.

Officers were called to the party on Hainsworth Avenue about 11:00pm on Friday after receiving reports 180 or so people were leaving the premises.

They said shortly after arriving they saw Kuol collapse.

He had earlier been riding around the street on a bicycle.

Members of Kuol's family said they believed he was assaulted and appealed for anyone with information to come forward.

The party had been advertised on Facebook.