Oculomotor palsy with cyclic spasms is a rare, non-progressive disorder in which the muscles innervated by the third cranial nerve undergo alternating rhythmic spasm and paralysis. An 18-year-old male was referred with left upper eyelid ptosis present since birth. On examination we noted cyclic movements of the left eyelid and pupil. The cycle consisted of periods of ptosis and mydriasis alternating with eyelid retraction with miosis. The interpalpebral fissure measured 2 mm in the paralytic phase and 11 mm in the spastic phase. The pupil diameter varied from 3 mm to 6 mm. Six cycles were observed in 5 minutes. The patient had no voluntary control over his left eyelid, nor over the other muscles innervated by the third nerve. The affected eye was deeply amblyopic and exotropic. Systemic evaluation and cranial MRI gave normal results. A therapeutic trial with oral baclofen (30 mg/day), a central muscle relaxant drug, was ineffective in suppressing the cyclic movements.