PURPOSE: To evaluate the efficacy of each phases in two and three phase spiral CT in the detection of pancreatic adenocarcinoma. MATERIALS AND METHODS: Two phase spiral CT images of 18 patients and three phasespiral CT images of 12 patients with pathologically-proven pancreatic ductal adenocarcinoma were retrospectively compared. Using a single spiral scan, images of early and delayed phases were obtained at 43 seconds and 2 ~ 3 minutes respectively initiating the after administration of 100-120 cc of contrast material (2 ~ 3 cc/sec),Images of arterial, portal and delayed phases were also obtained at 25 and 60 seconds, and 3 ~ 4 minutes,respectively, by the use of a double spiral scan. CT scans were performed with 10 mm collimation at 1 : 1 pitchtable speed. Contrast between the tumor and adjacent pancreatic parenchyma were compared and graded and enhancement pattern of the tumor were analysed together. RESULTS: In 12 patients (66.7%), images of the earlyphase were superior to those of the delayed phase. images of the portal phase were superior to those of thearterial phase. Enhancement of tumor was seen in four patients ; all tumors were less than 3cm in size. CONCLUSION: The early phase of two phase spiral CT is superior to the delayed phase and the portal phase of three phasespiral CT is superior to the arterial phase. Both arterial and portal phases are superior to the delayed phase.