Twenty-seven patients who developed cancer of the stomach after undergoing gastric resection (GR), gastroenterostomy (GE), and vagotomy and pyloroplasty (VP) for benign gastric or duodenal ulcer are reported. The etiology and the pathogenesis of this type of cancer are discussed. Long-term exposure of the gastric mucosa to bile and duodenal and pancreatic secretion reflux seems to create a premalignant potential state. Symptoms and the diagnostic methods of radiologic series, cytology, and endoscopy are discussed. We suggest a curative operative approach and discuss the poor value of palliative procedures. We emphasize the necessity of determining the prognosis with exploratory laparotomy which establishes at the same time the certitude of the diagnosis.