We report the case of a 40-year-old woman, with endometriosis, who presented with a history of foot drop and cyclic sensory disturbance of the right lower limb. She was initially diagnosed with lumbar disc herniation. Neurological examination revealed muscle weakness and sensory disturbance associated with the right sciatic nerve. Nerve conduction studies revealed a low amplitude sensory nerve action potential in the right superficial fibular and sural nerves. Pelvic magnetic resonance imaging revealed an endometriotic cyst in the right ovary, and an endometriotic lesion extending from the right ovary, pelvis, and the right sciatic nerve. Though her symptoms moderately improved with hormonal therapy, the foot drop remained. Our case and previous reports suggest that endometriosis with sciatic neuropathy shows cyclic neurological symptoms during menstruation, with a higher incidence on the right extremity. This case highlights that endometriosis should be considered as a potential differential diagnosis in women of reproductive age with sciatic nerve dysfunction. Its cyclic neurological manifestations should be investigated.