It happened around 2:00 Saturday morning near the intersection of Harbison Avenue and Comly Street.
The motorcyclist - a man in his 20s - was struck by a car and thrown from his bike. He was taken to Hahnemann Hospital in critical condition.
The striking vehicle fled the scene but was found on the 5300 block of Erdrick Street.
While the driver was taken into police custody, no formal charges have been filed.