The diagnostic accuracy of routine abdominal sonography for the detection of pancreatic cancer was examined. During the one-year period of 1994, sonographic examination of the upper abdominal region was performed 12,761 times on a total of 9410 patients for the screening of abdominal disorders. In 655 cases (7%) part of the pancreas could not be observed. Based on the "Diagnostic criteria for pancreatic cancer" published by the Japanese Society of Ultrasound in Medicine, sonographic finding was evaluated to be positive for pancreatic tumor in a total of 411 cases. At the end of 1995, 51 patients were proven to have pancreatic cancer, and 45 of these cases were ductal adenocarcinoma. In 26 cases the tumor was surgically resected. Fifty cases were true sonographic positives and one was a false negative. The sensitivity, specificity, overall accuracy, and positive and negative predictive values of sonography for pancreatic cancer were 98.0%, 95.9%, 95.9%, 12.2% and 100.0%, respectively. Among the 50 true positive cases, the tumor diameter was less than 1 cm in four (8%). In conclusion, the diagnostic accuracy of sonography for the detection of pancreatic cancer is sufficiently high. Therefore, a detailed study aimed at mass screening for pancreatic cancer using sonography as the main modality seems warranted as a countermeasure for the rapid increase of pancreatic cancer in Japan.