In spite of recent progress of body imaging diagnostics, such as ERCP, angiography, CT and conventional echosonography, the diagnosis of small pancreatic cancer is still restricted. Conventional US has progressed dramatically; however, intestinal gas or body wall often prevents the demonstration of deeper organs, such as the pancreas head and tail. The development of endoscopic ultrasonography has enabled us to demonstrate clearer imaging of the pancreas head and tail. From May 1980 to December 1983, we have used three types of ultrasonic endoscopy (Olympus and Aloka Co. Ltd.) with sector scan transducer (5.0 MHz or 7.5 MHz) and have examined 118 cases, containing 32 cases of pancreatic diseases. Among 15 cases of pancreatic cancer, 13 were demonstrated by type III (3 cases under 20 mm in size, 1 case between 20 to 30 mm, 9 cases over 30 mm). The scope was introduced into the upper G.I. tract in the same way as in conventional endoscopy. After the balloon tip of the scope was filled with water, scanning was started , having the balloon properly in contact with the duodenal or gastric wall. Cancerous lesions of the pancreas were clearly shown as a low echo mass in all cases. Each size of the lesions measured by EUS corresponded well to the resected specimens. Compared with other diagnostics, such as ERCP, CT, angiography and conventional US, EUS was the most useful method for detection of small pancreatic cancer under 20 mm in size.