A man was found with serious head injuries in a Yokine tavern toilet overnight.
Mirrabooka Detectives are investigating an incident which occurred on Thursday between 10:30pm and 11:45pm.
The 29-year-old victim was at the tavern on Wanneroo Road. He was taken to Sir Charles Gairdner Hospital and is in critical but stable condition.
A police spokeswoman said it was unclear how he sustained the injuries.
Detectives want anyone with information about the incident to contact them.
Information can be provided to Crime Stoppers on 1800 333 000.