Robbers stole several hundred pounds from a Bersted betting shop on Tuesday (August 2) night.
The two men threatened two members of staff at Ladbrokes in Chichester Road with sticks.
They also took the mobile phone of one of the male employees off the counter.
DS Russ Burgess, of West Sussex CID, said: “At this stage, we do not believe that this robbery is linked with other similar robberies in West Sussex recently.
“However, inquiries are in the early stages and we will not rule out this possibility.”
Neither of the staff was injured in the raid at 9.15pm.
The first robber is described as white, about 5ft 4ins, aged about 35 and with gingery stubble. He wore a patterned baseball cap, dark jacket, jeans and grey trainers.
The second man is described as white, about 6ft and stockily built. He wore a Nike shell suit top in various shades of blue and a hood over his face as well as black tracksuit bottoms.
Anyone with information which may assist enquiries is asked to contact Sussex Police on 0845 60 70 999 quoting serial 1997 of 2/8 or the independent charity Crimestoppers anonymously on 0800 555 111.