In the event of an acute condition within the abdomen, the differential diagnosis may often be made at home and without the aid of special laboratory investigation. Appendicitis accounts for two thirds of these emergencies. Other kinds of pathologic conditions may be difficult to recognize, but exact diagnosis is not always essential. However, even when an exploratory operation becomes compulsory, a tentative diagnosis guides the choice of a suitable surgical procedure. In these circumstances the surgeon primarily should find the answers to two fundamental questions: First, does the cause of the trouble really lie within the abdomen? Second, if definitely intra-abdominal, does the lesion require immediate operation or would delay favor the patient's welfare? The first step toward reaching a correct diagnosis obviously, is to obtain a concise history, most helpful when told by the patient in his own way. Pertinent details will be brought out later by skilful questioning.