The role of the computed tomographic (CT) scan in evaluating adults after their first seizure(s) was determined by reviewing the hospital records of 148 patients studied within 30 days of their ictus. Patients with alcohol or drug intoxication or withdrawal or with known brain tumor, craniotomy, or open skull fracture were excluded. Type of seizure; neurological, CT, and electroencephalographic findings; final diagnosis; and hospital outcome were cross correlated. The cause of seizure was established in 71 patients (48%); a structural lesion was identified by CT in 55 (37%), and 16 (11%) had metabolic seizures. CT findings agreed with the results of neurological examination 82% of the time. Structural lesions (including three tumors) were found by CT in 14 patients (15%) with nonfocal findings and in 12 (22%) of those with generalized electroencephalographic abnormalities. Our findings are similar to those reported in adult epileptics and lead us to conclude that the CT scan is a valuable aid in establishing the cause of seizures and in disclosing early lesions.