DURING the years 1935 to 1949 inclusive. 428 patients with acute perforated peptic ulcer were treated at the Cincinnati General Hospital. This report is concerned chiefly with the 128 patients who were seen during the past five years and who received penicillin as a part of their treatment. The other patients have been reported on previously and are used for comparison of the results of treatment.1 The purpose of this analysis is, first, to determine whether immediate operative treatment of peptic ulcer, after the use of proper supportive measures, is justifiable in the face of the remarkable results which have been reported with the nonoperative method of treatment and, second, to consider briefly the question of immediate gastric resection in selected cases of perforated ulcer. The treatment of acute perforated ulcer at the Cincinnati General Hospital, as developed over the past fifteen to twenty years, has been operation, with