Computed tomography of the head (HCT) was studied prospectively in 42 new geriatric psychiatry patients. Scans were obtained in 88% of the sample. Subjects underwent a complete evaluation by a geriatric psychiatrist who was blind to the HCT results. The HCT was abnormal in 32 (86%) of the 37 patients who had a scan. The most frequent finding was atrophic changes, which were discovered in ten (27%) of the 37 patients. Subcortical vascular disease was found in 14 patients (38%). Mixed pictures with both vascular disease and atrophic changes were found in nine (24%). The only statistically significant predictor of an abnormal HCT was an abnormal neurobehavioral examination. While the information gained from the HCT did not add appreciably to the clinical evaluation in determining whether there was an organic or idiopathic psychiatric syndrome, it was crucial in determining the location and nature of the central nervous system lesions.