A cyclist is in a serious condition at Sir Charles Gairdner Hospital, as police seek public help to try to identify him.
Traffic officers and paramedics found the man collapsed on the Reid Highway Overpass near the Mitchell Freeway in Balcatta just before 7 o'clock this morning.
The unidentified man was unable to speak to officers and was not carrying and identification.
He's described as 40 to 55 years old, fair skinned and about 183 centimetres tall, and was wearing a grey t-shirt, blue and black board shorts, red Diadora cycling shoes and black socks.
The bicycle is a black, red and white Cervelo.
Anyone who has information should call police on 131 444.