Fahr syndrom is a rare idiopathic basal ganglia calcification that is accompanied with psychosis movement disorders, mental retardation and so on. This is a report of a 32 year old woman who was admitted in the psychiatric ward of Emam Hossein hospital in 1998. Before her 8 months stay in hospital, she had been symptomatically insidious with headache, insomnia, withdrawn, and self-talking. In mental status examination, she showed blunted affect, poverty of though content, auditory hallucination, attention, concentration, recent memory impairment and gait disturbance. Ca, P, Alk Ph and PTH were in normal limit. IQ test revealed slight retardation and Bender-Gestalt test proved mental disturbances.