Laparoscopy and hysteroscopy were simultaneously performed to examine the intraperitoneal and intrauterine spread of endometrial cancer prior to surgery. Peritoneal cytology (PC) was examined before and after hysteroscopy and at the time of laparotomy. To elucidate the mechanisms by which endometrial cancer cells spread into the peritoneal cavity, the changes in PC in sequential samples and the association between PC and other prognostic factors were examined. 1) Of the patients who had negative PC before hysteroscopy, 3 patients exhibited positive PC from their operation materials (12.5%). It was suggested that leakage of endometrial cancer cells into the peritoneal cavity was induced by hysteroscopy in 2 patients and by endometrial biopsy in one patient. 2) Of those patients with no intraperitoneal lesions, 3 patients had positive PC in the prehysteroscopy samples (11.1%). A statistically significant association was found between pelvic node metastasis and positive PC in the prehysteroscopy samples.