Eleven patients, 7 males and 4 females, of progressive supranuclear palsy (PSP) were examined neuro-otologically for the purpose of elucidating the characteristics of ocular motor abnormalities. All cases were admitted to our hospital and age at onset was from 52 to 71 years old, duration of illness was 2 to 11 years. Range of voluntary eye movements and abnormal eye movements including nystagmus were examined on naked eyes and with electronystagmography (ENG). Smooth pursuit movements and saccadic eye movements were tested both horizontally and vertically by using visual tracking method with ENG recordings. Optokinetic nystagmus test and caloric test with visual suppression test were also performed. These neurotological examinations were made repetitively in 5 cases and their progressions were observed. Vertical gaze palsy and convergence palsy were observed in all cases as the initial symptom. In this study downward gaze was more severely disturbed than upward gaze. Using ENG, saccadic eye movements (saccades) were disturbed earlier than smooth pursuit movements. Hypometric saccades and decreased saccadic velocity were common abnormalities. In the later stage of the disease, horizontal eye movements were also disturbed. In four cases bilateral adduction palsy was added to vertical gaze paralysis so that the lesion of the MLF to oculomotor nucleus was suggested to exist. These voluntary eye movements were worsened gradually as the disease progressed. By using ENG we could find so called abnormal eye movements more frequently than the previous reports. Eight patients demonstrated horizontal gaze nystagmus, and rebound nystagmus were observed in four cases.(ABSTRACT TRUNCATED AT 250 WORDS)