There is cognitive impairment in schizophrenia, most likely due to some kind of brain dysfunction which has yet to be precisely identified. Several brain regions have been implicated, including the frontal and temporal lobes. Patient show a great deal of heterogeneity in terms of what cognitive functions are impaired and how severe the impairment is. Approximately half of patients diagnosed with schizophrenia show significant cognitive impairment and evidence for cerebral atrophy on CT. Chronicity, length of hospitalization, or medications cannot fully account for these findings. Neuropsychological testing can aid in diagnosis, treatment planning and prognosis. Therapies which have been used for brain injured patients have been attempted with schizophrenic patients with some success. Neuropsychologists working in psychiatric settings can make a valuable contribution to the clinical evaluation, diagnosis, treatment and scientific study of persons with schizophrenia.