To provide evidence of an organic pathology for essential (idiopathic) blepharospasm, reflex saccadic eye movements in response to randomly stepped visual targets were assessed in seven affected patients and seven age-matched controls using the magnetic scleral search coil technique. The results indicate a significant prolongation in latency and a reduction in gain of horizontal saccades, and an increase in latency and reduction of peak velocity of large downward saccades. These findings suggest an organic component to the aetiology of blepharospasm, the pathology of which also appears to involve the oculomotor system. The pattern of the oculomotor disorder does not allow specific localisation but is consistent with the underlying pathology being localised in the basal ganglia.