A 28-year-old man is in Royal Perth Hospital with a fractured skull after being found unconscious on the side of a road in Southern River yesterday morning.
Armadale Detectives are currently working to establish the events that led to the man being unconscious and on the side of Barrett Street.
About 6.20am Thursday, a member of the public located the man about 2-3m off the side of the road and called police.
Police attended and St John Ambulance was called; he was taken to Armadale Hospital where it was established he had a fractured skull and possible bleeding on the brain.
He has since been taken to Royal Perth Hospital where he is in a serious but stable condition.
The man was wearing black pants and T-shirt, a black leather jacket, black baseball cap and may have been riding a silver mountain bike.
Police would like to speak to anyone that saw the man in the area at the time, or has information that could assist Detectives with their investigation.
Call Crime Stoppers on 1800 333 000 or to make a report online.