The robbery happened around 11:20 a.m., in the Wells Fargo bank at the corner of N. Glebe Road and Lee Highway.
Police say two black males entered the bank, displayed a handgun, and ordered everyone inside to the floor. The elderly woman was hurt when one of the robbers threw her to the ground, said Arlington County Police Department spokesman Dustin Sternbeck.
The men fled the scene with an undetermined amount of money and remain at large. The woman was transported to Virginia Hospital Center with minor injuries, Sternbeck said.
Police hope to release surveillance images of the suspects later today.