Endometrial carcinoma is the most common malignant tumor of the female genital tract in the Western world. Approximately 80% of cases are well- to moderately differentiated (endometrioid) adenocarcinomas, which are confined to the uterine corpus at diagnosis, and thus most can be cured. Conversely, high-grade (ie, clear cell and serous) carcinomas account for only 15% to 20% of cases and show marked nuclear atypia. These tumors usually invade the myometrium and may extend beyond the uterus at the time of hysterectomy. In addition to clinical and morphological differences, these 2 groups of endometrial carcinomas differ in their pathogenesis. Whereas prognosis in the latter group is generally poor, the pathologist's role in establishing the outcome in the former group is crucial. Furthermore, it has become progressively apparent that both groups overlap to some extent, making the dualistic model a guideline at best. Over the last 2 decades, several studies have demonstrated the prognostic importance of various key surgical and pathological parameters, including histological type, histological grade, surgical-pathological stage, depth of myometrial invasion, vascular invasion, and cervical involvement. This review presents the most important prognostic factors of endometrial carcinomas from the pathologist's viewpoint, and attempts to clarify existing conflicts in the classification and diagnosis of these tumors. (C) 2004 Elsevier Inc. All rights reserved.