A prospective diagnostic study was designed to determine the ability of thin-section contrast-enhanced computed tomography (CT) to predict the resectability of malignant neoplasms of the pancreatic head. Patients with a presumed resectable pancreatic neoplasm referred during a 21-month period were studied with abdominal CT performed at 1.5-mm section thickness and 5-mm slice interval during the bolus phase of intravenous contrast enhancement. CT criteria for resectability included the absence of extrapancreatic disease, no evidence of arterial encasement, and a patent superior mesenteric-portal venous confluence. Of 145 patients evaluated, 42 were considered to have resectable tumors by CT criteria, and 37 (88%) underwent potentially curative pancreaticoduodenectomy. Six patients were found to have a microscopically positive retroperitoneal resection margin; no patient had a grossly positive resection margin. Five (12%) of 42 patients were found at laparotomy to have unresectable, locally advanced or metastatic tumors. Thin-section contrast-enhanced CT is an essential component of the preoperative evaluation for pancreaticoduodenectomy and can prevent needles laparotomy in most patients with locally advanced or metastatic disease.