The operative procedure of prefrontal lobotomy was done on a group of 13 patients with severe depression, agitation, and apprehension to ascertain whether relief could not be obtained from their symptoms and, at the same time, to determine whether the operative procedure affects the mental abilities of these psychotic individuals. Social histories were obtained, detailed progress notes made, and the Stanford-Binet Intelligence Examination was administered before and after the operation. On 11 of these patients the operation was performed on both prefrontal lobes; and on the 2 other patients the operation was done on one lobe only[long dash]the left lobe on 1 patient, and the right on the other. After the operation there was a definite increased psycho-motor activity, together with a corresponding emotional uplifting. There were no consistent changes in the intellectual capacities as measured by the Stanford-Binet examination except for the free association test on yr. 10. Only 1 patient of those tested was able to pass this test after the operation. Lack of a control group and criteria for objective evaluation of social adjustment preclude valid conclusions as to the therapeutic efficacy of operation.