Police are investigating after a robber stole cash from Labrokes betting shop in Broadwater on Saturday evening, a spokesman said.
Police said the robber entered Ladbrokes in Broadwater Street East, Broadwater, shortly after 9pm.
He stole cash before fleeing on foot in a westerly direction towards Broadwater Green, according to police.
Police describe the suspect as a white man, 6ft, in his early 20s, of slim build and possibly with a beard.
He was wearing a blue hooded jacket with the hood raised, jeans, trainers and a scarf, added police.
Police said: “Threats were made to staff to hand over money but no one was hurt.
“Anyone who saw what happened, noticed anyone acting suspiciously or who may have other information is asked to contact Sussex Police online or phone 101, quoting serial 1180 of 12/01.
“Alternatively please contact the independent charity Crimestoppers anonymously on 0800 555 111 or via its website, www.crimestoppers-uk.org.”