Contrast-enhanced computerized tomography (CT) is frequently utilized immediately after surgery to determine the presence of residual tumor, but the response of nontumor brain tissue is unclear. Consequently, the authors investigated the postoperative CT contrast enhancement in six patients undergoing lobectomy for epilepsy. Preoperative CT scans were obtained in all cases and revealed no enhancing lesions. All patients underwent craniotomy with electrocorticography while awake, followed by lobectomy. Computerized tomography scans with and without administration of contrast material were obtained on postoperative Days 3, 7, and 30. Edema, artifact, and enhancement of the resection margins were seen on postoperative Days 3 and 7, but had resolved in all patients by Day 30. It is concluded that postoperative CT scans for assessment of residual tumor are best obtained at 30 days or thereafter, when normal brain does not enhance and edema and artifact have diminished.