A 39-year-old woman presented with psychiatric signs and symptoms of major depression. After psychiatric hospitalization for 2 months, she developed neurologic signs. A magnetic resonance image showed dilated ventricles and a craniopharyngioma compressing the midbrain area. Neurosurgical drainage of the cyst resulted in immediate remission of all major depressive features. The revised diagnosis was that of organic mood disorder, depressive type. There have been no symptoms of depression in over 18 months follow-up.