Flow cytometric analysis of cell cycle kinetics from paraffin-embedded tissues was performed to evaluate the DNA heterogeneity and risk factor of endometrial adenocarcinoma. We studied 54 tumor samples and 6 controls with normal endometrium, and all samples were measured for S-phase fraction (SPF) and proliferative index (PI). Intratumor variations of SPF and PI values were evaluated at 3 different sites of the tumor; (1) primary endometrial lesion, (2) the site of myometrial invasion, and (3) metastatic lesions. SPF and PI values of endometrial adenocarcinoma were significantly higher than those of normal endometrium. There was a significant correlation between the PI value and the histological grade. SPF and PI values at the primary endometrial lesion had a significant correlation with the prognosis of this cancer at stage III or IV. SPF and PI values which were measured at the site of myometrial invasion tended to be lower than those from other sites. Our results indicate that the SPF and PI values of endometrial lesions are one of the important prognostic factors of endometrial adenocarcinoma at stage III or IV. In addition, DNA syntheses of endometrial adenocarcinoma cells display intratumor heterogeneity.