Clinicopathological and DNA ploidy studies were carried out to evaluate the prognostic factors of gastric cancer invading to the layer of muscularis propria. Seven hundred and ninety four patients with gastric cancer underwent gastrectomy between 1980 and 1988. Of these 85 were found to be "pm" gastric cancer. The unfavorable prognostic factors were as follows: 1) location of the tumor in the upper third of the stomach, 2) deeper cancer invasion in the muscularis propria, 3) presence of lymphnode in which cancer cells involve more than half of its histological section and 4) DNA aneuploid cancer.