The use of ultrasound in the non-invasive investigation of the biliary tract and pancreas is discussed. Its accuracy in detecting gallstones in the non-acute condition is as accurate as conventional radiography, which is dependent on the excretion of contrast medium by the liver. Ultrasound is not dependent on liver function and has become the best initial investigation in persistent jaundice, acute cholecystitis, acute pancreatitis, and chronic pancreatic disease. In a retrospective study of 75 patients with acute pancreatitis liver function tests were found to be abnormal in 67% and contrast radiography proved to be of limited value. Ultrasonography performed shortly after admission showed an overall accuracy of 82% correct findings. The identification of gallstones in pancreatitis and cholecystitis permits early surgery, which reduces morbidity, improves prognosis, and is now being accepted as the treatment of choice.