We report a case of pituitary apoplexy occurring in a 74-year-old patient 6 hours after cardiac surgery. The patient presented with confusion, unilateral ptosis and ophthalmoplegia. Neurological examination revealed right oculomotor nerve palsy and decreased level of consciousness. Magnetic resonance imaging showed a hemorrhagic and necrotic pituitary macroadenoma. After prompt endocrinological replacement therapy with hydrocortisone and levothyroxine, the confusion of the patient resolved. Removal of a non-functional macroadenoma with large necrotic areas resulted in full recovery. The physician should be aware of pituitary adenoma infarction after open cardiac surgery and should remember that it can be fatal or cause permanent neurological or endocrine damage without proper treatment. Surgical and endocrine treatment can be life-saving procedures.