Plasma cortisols in 18 abdominal emergency patients and 20 planned-operation patients were examined. The result showed that cortisols in planned-operation patients were increased after their operations. On the other hand, plasma cortisols in emergency patients were higher in preoperative period than that in the postoperative period. There were no furher increase after operations. The changes of plasma cortisols between two kinds of patients were very different. This means that stress reactions in the patient with acute abdomen can be reduced by early operations.