At the McGill University neuro-ophthalmology unit, 52 patients with superior oblique palsy were seen during the 2-year period October 1973 to August 1975; these included patients with congenital, traumatic, vascular, and other more rare causes of trochlear paralysis. Half of the patients with congenital palsy had diplopia, requiring treatment, although surgery was rarely necessary. Patients with palsy due to trauma, the major cause in our series, included four with bilateral involvement. With the exception of recovery in a single muscle of one patient in this group with traumatic palsy, no spontaneous recoveries have been observed. Treatment modalities have been tried, including observation alone, occlusion for symptomatic relief of diplopia, use of prisms, and recession of the ipsilateral inferior oblique muscle. Four patients with palsy of presumed vascular cause recovered spontaneously within a 4-month period. All patients who were surgically treated improved.