Thirteen samples of gastric tumors that had developed in the remnant stomach (remnant gastric cancer) were compared with 63 samples of primary gastric tumors located in the upper third of the stomach (primary gastric cancer) by both clinicopathologic and flow cytometric analysis. The depths of invasion of all these tumors corresponded to the mucosa, submucosa, or muscularis propria layers and the histological stages were stages I, II, or III. There was no significant difference between the two groups of samples either histopathologically or clinically (the 5-year survival rates were 74.6% for patients with remnant gastric cancer and 90.4% for patients with primary gastric cancer). DNA aneuploidy was encountered in 23.1% of the cases of remnant gastric cancer and in 33.3% of the cases of primary gastric cancer. Little difference was found in the S-phase fractions between tumors and normal gastric mucosa of the upper third of the stomach and the remnant stomach. Thus, while the environments in the upper third of the stomach and in the remnant stomach are very different, histopathological and biological characteristics of adenocarcinomas that developed in the remnant stomach are very similar to those of adenocarcinomas in the upper third of the stomach.