Leg pain and foot drop are caused most frequently by herniated disc disease of lumbar spine. However, they also can be caused by compression of the peroneal nerve. Here we present a case of a 52-year-old woman who developed progressive foot drop as a result of compression of the common peroneal nerve by an intraneural ganglion cyst. Surgical excision was subsequently performed. At 1-year follow-up after surgery, her neurological status was slightly improved, but weakness in dorsiflexion of the foot was still noted. If preoperative electromyography shows denervation of the tibialis anterior muscle, complete resolution of palsy is less likely. Intraneural ganglion cyst of the peroneal nerve should be considered when patients present with the symptoms of leg pain and foot drop.