The 5 yr survival rate of 78 patients with carcinoma of the ovary showed that the prognosis was significantly better when the tumor modal DNA value was in the diploid region than when it was near-triploid or above. Similar data on 140 patients with carcinoma of the breast and 52 with carcinoma of the bladder also suggested a better prognosis for the near-diploid tumors. Among 105 carcinomas of the large bowel, there were more survivors in the high ploidy than in the near-diploid group, although the difference was not statistically significant. The varying relationship between ploidy and prognosis, depending on the site or histological type of the tumor, is briefly discussed on the basis of the 1171 cases included in the present and a previous paper.