There are welfare concerns for Thomas 'Eddie' Power, who was last seen at Fiona Stanley Hospital where he was receiving medical treatment.
The 65-year-old resides in North Lake but is known to frequent the Mandurah area.
He is described as 170cm tall with a slim build, green eyes, light brown hair and has several tattoos on both forearms.
Police believe he is travelling on foot and it is not known what clothing he was wearing when he disappeared November 5.
Anyone with information is urged to contact Police on 131 444 and reference IR 131120 1000 16896.
Mandurah Crab Fest boasts huge range of free, family friendly entertainment
Fuel prices surge in Perth, Mandurah
Teen boys charged over Mandurah burglaries
Tragic update in search for missing man Robert Snyder
Premier Roger Cook to leave Kwinana electorate, move to Perth
Mandurah Marine Rescue's new vessel named in memory of nun who survived 1959 boating accident
Teen dies in motorbike crash at Waroona Dam
Shark alert issued after whale carcass reported at Preston Beach
Kwinana businesses to refuse serving students during school hours