AT THE Presbyterian Hospital of Chicago, from January, 1950, to June, 1953, there were 140 cases of peptic ulcer in which gastric resection was done. Eleven patients were operated on for severe hemorrhage. In five of these no source of bleeding was found at exploration. This report is of these five cases. The nature of the lesions and the results of treatment are presented, and a program for surgical treatment of such cases is proposed. REPORT OF CASES Case 1. —(W. H., Admitted Oct. 12, 1952; died Oct. 18, 1952.) A 73-year-old retired white man had had four admissions during the previous nine years, once for suprapubic prostatectomy and tonsillectomy and three times for medical observations of focal cerebrovascular accidents. On the morning of the latest hospital admission, he had suddenly passed large amounts of grossly bloody stools, followed by a massive hematemesis of bright-red blood. The patient fainted in