Thermography appears to be a useful supporting aid to classical methods of examination in the clarification of the problems of acute abdominal disease. In a study of 100 patients thermography was in support of the true diagnosis in acute appendicitis in 63 per cent, in acute biliary tract disease in 59 per cent, and, in an attempt to differentiate between tumor and periappendicular abscess, assistance was rendered by thermography in 53 per cent of patients. However, some uncertainty exists because carcinoma often produces in its environment an inflammatory reaction, which causes an increase of temperature visible in the thermogram. In the present series thermography produced a finding supporting the correct diagnosis in 59 per cent. Errors occurred most often in obese patients, who have thick abdominal covers. Thermography also has an obvious application in the localizing of postoperative suppurative foci.