Police are on the hunt for a man who threatened staff with a knife during a hold-up at a DVD hire store at Gawler, north of Adelaide.

They say the suspect entered the Blockbuster store at about 8.30pm, threatened the staff member, and then fled on foot with an amount of cash.

No one was injured in the incident.

The man is described as Caucasian with an olive complexion and shoulder-length black hair tied in a pony tail, with a thin black beard and moustache.

He is aged in his mid to late twenties, about 175cm tall with a thin build and a gaunt appearance.

He was wearing a chequered hoodie top, black track pants, black baseball cap and dark sunglasses.