Thirty-six cases of a heterochronous cancer in the remnant stomach following a partial gastrectomy for gastric cancer have been compared with 12 cases of gastric cancer following a gastrectomy for benign diseases. Lesions of a heterochronous cancer are characteristically similar to those of a synchronous multiple gastric cancer. Patients with a heterochronous cancer were found to have high rates of synchronous multiple cancers in the resected stomach as compared with none found in gastric cancer patients following surgical operation for a benign disease. Lesions of cancer after surgery for a benign disease when found were mostly in the anastomosis of the remnant stomach. These findings suggest that a heterochronous gastric cancer may develop into lesions of multiple cancers.