40 gastric stump carcinomas have been investigated. The results are compared with 72 gastric carcinomas without preceding Billroth II resection. The aim of this study was to contribute to our knowledge about the pathogenesis of gastric stump carcinoma. The mean age of patients with gastric stump carcinoma and with carcinoma without preceding Billroth II resection is identical. The age distribution, too, is similar in both groups. Furthermore the time of the Billroth II resection for benign peptic ulcer shows no correlation with the appearance of the gastric stump carcinoma, which suggests that there is no constant time lag between Billroth II resection and stump carcinoma. The histological investigation of the tumor-free gastric mucosa shows similar alterations in the two groups compared. Intestinal metaplasia and cystic dilatation seems to be more common in the gastric mucosa after Billroth II resection as compared with the non-tumorous mucosa of patients without preceding Billroth II resection. But the grade of nuclear atypia in non-tumorous mucosa is identical in both groups. Interestingly enough, the frequency of the main types of gastric cancer, intestinal carcinoma and diffusely infiltrating carcinoma is very similar. Thus, both the epidemiological and histological data seem to indicate that the pathogenesis of gastric carcinoma is very similar to that of gastric carcinoma without preceding gastric surgery. The Billroth II resection does not seem to be a main factor in pathogenesis, but may have co-factorial significance.