The CVS on City Avenue was robbed early Tuesday morning, Lower Merion police said.
Two black men standing between 5 feet 4 inches and 5 feet 11 inches tall entered the 24-hour store about 4:55 a.m., announcing a robbery and ordering all three employees into a back room, police said.
One employee opened a safe and removed cash as one of the robbers displayed a handgun.
There were no reports of injuries.
It was the first robbery reported at the pharmacy since two men made off with an undetermined amount of cash May 21.
Anyone with information about the robbers may call police at 610-649-1000.