THE DEVELOPMENT of gastrojejunal ulceration following an anastomotic operation for peptic ulcer must obviously be accepted as an indication of unsuccessful surgical treatment of the ulcer diathesis. Ninety patients with gastrojejunal ulceration have been treated at the University of Illinois Research Hospital and the Hines Veterans Administration Hospital during the period 1946-1954, and are the subject of this report. The great majority of these patients had had their initial surgery performed elsewhere. Gastrojejunal ulceration occurred after gastroenterostomy in 46 patients, after partial gastrectomy in 31 patients, and after gastroenterostomy and vagotomy in 13 patients. It has been long recognized that gastroenterostomy exerts no beneficial effect on the ulcer diathesis, and, hence, gastrojejunal ulceration following the performance of this operation is easily understood. Yet, although both subtotal gastric resection and vagotomy associated with gastroenterostomy are alleged to be effective in treating the ulcer diathesis, gastrojejunal ulceration occurred in this study in