A 73-year-old woman was assaulted earlier this month when she out walking near Spring Road in Thornlie.
On January 17, at about 6.20pm a man walking near by approached the woman.
He allegedly punched the woman in the head before walking off.
He was last seen walking towards Gosnells.
The offender has been described as pale skinned with a grey weathered complexion and is said to be between 40 and 50 years old.
He is about 170 to 175 centimetres tall, of slight build with scruffy greying hair and a beard and blue grey eyes.
He was last seen wearing a black dark navy long sleeved windcheater and track pants.
Canning Vale Police are seeking information regarding the assault and have asked anyone with any information to call Crime Stoppers on 1800 333 00 or make an report online at crimestopperswa.com.au