The incident took place shortly before 7:30 p.m. Saturday at the Rite Aid on the 8700 block of New Falls Road in Levittown, Falls Township.
Police say the suspect entered the store, displayed a revolver handgun, and demanded money.
The male took an undisclosed amount of money and fled east on New Falls Road in a white vehicle with Pennsylvania registration plates.
The suspect is described as a white male, approximately 6' tall with a thin build, last seen wearing a navy blue hooded jacket, blue jeans, white sneakers, dark color baseball cap, a black bandana, black sunglasses and blue gloves.
No injuries were reported.
Anyone with information should contact Detective Stephen Reeves at (215)-302-3305.