In most cases of isolated oculomotor nerve palsy in 30 patients under age 20 years the palsy was congenital, and aberrant regeneration was present. The most common causes of acquired oculomotor nerve palsy were blunt trauma and infectious processes, both local and systemic. Neoplasms, aneurysms, and ophthalmoplegic migraine caused the other cases. The causes of isolated oculomotor nerve palsy in childhood differ from those in adults both in nature and in frequency of occurrence.