The synchronous occurence of primary carcinomas of endometrium and ovary is well recognized. Malignant peripheral nerve sheath tumours (MPNSTs) may also rarely occur in patients diagnosed with malignancies of the female genital tract. We report a rare case of synchronous primary carcinomas of endometrium and ovary, followed by a metachronous retroperitoneal MPNST. Ascites cytology and endometrial biopsy, followed by hysterectomy and bilateral adnexectomy, were performed to remove the synchronous tumors. Histology was suggestive of synchronous endometrial endometrioid carcinoma and ovarian mucinous adenocarcinoma. After the removal of the retroperitoneal tumor, a MPNST was diagnosed by immunohistochemistry. The patient developed two consecutive vaginal tumors diagnosed as metastases of the previously diagnosed endometrial carcinoma. Although synchronous tumors of endometrium and ovary were relatively early staged and consequently had a favorable prognosis, subsequently occuring implants along the lower genital tract and the metachronous MPNST added up to a poor prognosis.