peritoneal cytology as a test for the detection of malignant cells in the peritoneal cavity is limited by the size of the study populations, varied use of preoperative radiation, the lack of consistent methodology for specimen retrieval and processing, and the inherent subjectivity of cytologic interpretation. A standardized methodology for retrieval and processing of peritoneal cytologic specimens should be developed to allow meaningful comparisons of future studies. However, certain conclusions are permitted from published data: 1. The incidence of positive peritoneal cytology is 11.4 per cent among 3091 patients with FIGO stage I endometrial cancer. 2. The depth of the uterus does not influence the incidence of positive peritoneal cytology. 3. Positive peritoneal cytology is predictive of other known prognostic factors including advanced histologic grade, depth of myometrial invasion, and pelvic/periaortic lymph node metastases. 4. The presence of malignant cells in the peritoneal washings from some patients with no myometrial invasion and the high incidence of lymph node metastases in other patients with positive peritoneal cytology suggest that malignant cells gain access to the peritoneal cavity in a variety of ways. While positive peritoneal cytology is no longer included among the endometrial cancer staging criteria, Federation International de Gynecologie et Obstetrique recommends continued collection of pelvic washings for cytology to produce additional data that may be used to determine the significance of positive cytology for prognosis and treatment of endometrial cancer.