Puma Pearsall is the latest petrol station to be held up in the northern suburbs after an incident on Wednesday morning.
WA Police spokeswoman Susan Usher said that a man with a knife threatened a staff member at the petrol station on the corner of Lenore Street and Ocean Reef Road about 2.50am, demanding cash.
She said he fled with the cash on foot, and was last seen running north-west along Shiraz Boulevard.
The offender is described as being possibly in his late 20s to early 30s, fair-skinned, about 170-175 centimetres tall and solidly built, wearing a dark hooded jacket and dark trousers.
Many other petrol stations around Perth have been hit by armed robbers during May, including in Jolimont, Padbury, Butler, Barragup and Lakelands.
Anyone with information should call CrimeStoppers on 1800 333 000 FREE.
Extracted in full from WA Today.