In 95 patients with acute abdominal pain seen in the emergency ward of a large urban teaching hospital, real-time sonography was performed in conjunction with a plain film of the abdomen in order to detect what, if any, added information was provided by the sonographic examination. In 20 patients (21%) the sonogram contributed important diagnostic information not provided by the plain film of the abdomen. Most of these patients had pathology referable to the biliary tract (14 of 20). In 28 patients (30%), the sonogram confirmed the diagnosis by abdominal film. In 39 (41%) the sonogram added no relevant information, and in three (3%) it was deleterious. In five (5%) the plain film provided more information than the sonogram.