Visual field defects, is the most common presenting sign of pituitary tumors. Acute painful third nerve palsy with pupillary involvement is a well known presenting symptom of a posterior communicating artery aneurysm. Oculomotor palsy with pupillary involvement is a relatively uncommon initial sign of a pituitary adenoma. This report describes a patient who presented with isolated oculomotor palsy with pupillary involvement which on neuroimaging was found to be due to a pituitary macroadenoma with cavernous sinus invasion. We suggest that differential diagnosis of painful oculomotor palsy must also include pituitary adenomas which rarely present with isolated third nerve palsy.