Peritoneal cytology has been shown to be one of the prognostic factors in endometrial cancer. A series of 134 patients was seen between January 1977 and March 1985 with clinical Stage I (or treated as a clinical Stage I) endometrial adenocarcinoma at the University of Rochester Cancer Center. The majority of patients underwent extrafascial hysterectomy with the majority of washings obtained at the time of surgery. Fourteen percent (19/134) of the patients were found to have positive cytology. Eleven patients with positive cytology (11/19) were treated with local-regional pelvic treatment; the other eight patients received whole abdominal therapy. The recurrence rates were less with the local treatment than with the whole abdominal treatment groups (9.1% vs. 25%) in those patients having positive cytology. There was no statistical difference in recurrence rates between the pathologic Stage I patients with positive cytology (10%) versus those patients having negative cytology (5%), nor was there statistical difference in survival between pathologic Stage I positive or negative cytology patients. It is suggestive from this non-randomized study that positive cytology in endometrial cancer is not an independent prognostic factor and that whole abdominal irradiation did not influence outcome.