The robbery happened around 5:30 a.m. on Sunday, May 5th outside the Wells Fargo Bank at 3400 Aramingo Avenue.
The woman had just made a withdrawal of $80, police say, when a man approached her, put a knife to her stomach, and demanded the money.
After taking the woman's cash, the suspect fled south on Aramingo Avenue.
The suspect is described as white male in his late 20s standing 5'5" tall with a skinny build. He was wearing a black hat, a tan and beige jacket, a blue shirt and blue jeans.
Anyone with information is asked to contact Philadelphia Police at 215-686-TIPS (8477), text a tip to PPD TIP (774847) or through PhillyPolice.com.