Endoscopic ultrasonography has been applied to 30 patients with suspected pancreatitis. All were difficult clinical problems which had not been resolved by conventional ultrasonography. CT scanning, and pancreatography. There were 7 technical failures where the instrument could not be advanced through the pylorus. A definite result was produced in 23 patients. In 7 the EUS findings were confirmed by histology obtained at surgery. In 6 a definite diagnosis of mild chronic pancreatitis was made. Previously undescribed morphological features such as peri-ductal fibrosis, branch duct ectasia and lobular inflammation were shown and correlated with the histological appearance. In 10 patients an EUS diagnosis of a normal pancreas has not been challenged after clinical follow up of six months to two years. The high resolution of EUS is capable of showing unique morphological detail in pancreatitis.