The robbery happened around 1:00 p.m. Wednesday at 5607 Vine Street.
Investigators say the man handed a teller a threatening demand note and got away with an undisclosed amount of cash.
The suspect was described by police as a white male, 20 to 30 years old, six feet tall with a medium build, dirty blond mustache and goatee, wearing a multi colored white shirt worn over a gray long sleeved t-shirt.
Anyone with information is urged to contact Philadelphia Police at 215-686-TIPS (8477), text a tip to PPD TIP (773847) or through PhillyPolice.com.
