In this case report, we describe a case of isolated oculomotor nerve palsy associated with antibodies to mitotic spindle apparatus (anti-MSA). A 28-year-old female patient had acute, painful vertical diplopia. She had limited depression and adduction in the right eye. There was no relative afferent pupillary defect. Brain magnetic resonance imaging showed no abnormal findings. Laboratory tests were all negative, with the exception of positive anti-MSA, She had an excellent and rapid response to treatment with corticosteroids, and completely recovered after two weeks of steroid pulse therapy.