Our objective was to assess the detection rate and the accuracy of tumor size determination in pancreatic ductal adenocarcinoma using dynamic computed tomography (CT). Preoperative dynamic CT was evaluated in 35 surgically resected pancreatic ductal adenocarcinomas and the findings were compared with the results of histopathological examination. Pancreatic adenocarcinoma was visualized by dynamic CT as a low-density mass in 97% of cases, All three lesions less than or equal to 2 cm in size were demonstrated in good contrast to normal pancreatic parenchyma, The tumor size measured on dynamic CT showed a good correlation with that measured histopathologically, especially in small tumors. Dynamic CT was useful for evaluating the extent of pancreatic adenocarcinoma, especially for small tumors. The detectability of lesions by CT depended on the manner of tumor extension and the degree of associated pancreatitis as well as the tumor size.