Five hundred and four asymptomatic patients in whom gastrectomy had been performed between 1931 and 1960 were investigated by endoscopy plus biopsy. Ten stump carcinomas were detected (1.98%). In five patients the tumour was limited to the mucosa and was not seen at endoscopy. In three patients with previously noted severe dysplasia intramucosal carcinoma was detected during follow up and in two the carcinoma was found at the site of the preceding severe dysplasia. True regression of severe dysplasia could not be shown. In 23 patients with previous mild or moderate dysplasia no progression was seen during follow up. Severe gastric dysplasia is a serious marker of malignancy demanding close follow up with repeated endoscopy and biopsy. The clinical significance of mild and moderate dysplasia remains unclear. Early detection of stump carcinoma is indeed possible. Physicians should rely not so much on the endoscopic appearance but on the results of multiple biopsies.