A rare case of a patient with a histopathological diagnosis of a sarcomatous-type peritoneal malign mixed mullerian tumor implant in association with ovarian adenocarcinoma is reported. A 52-year-old patient was referred to our clinic for an adnexal mass. At pelvic examination, an irregular, fixed, approximately 7-8 cm in size mass was detected in the right adnexal area. At transvaginal ultrasonographic examination, it was observed that there was an 80 x 70 mm sized, irregularly contoured, semisolid mass with hyperechogenous areas inside originating from the ovary in the right adnexal area. At laboratory examination tumor marker CA-125 was 280.4 U/ml (< 35), CA-15-3 was 146.5 U/ml (< 25), whereas other markers were within normal range. The patient was operated on for a right adnexal mass. A staging laparatomy procedure was applied. Postoperative histopathological diagnosis was reported as malignant mixed mullerian tumor of the ovary, with the ovarian component as poorly differentiated adenocarcinoma, and the metastatic foci over serosal surfaces as a sarcomatous component. Postoperatively six courses of adjuvant and consolidation chemotherapy were administered to the patient. Further studies are needed to set a consensus about evaluation of treatment and prognosis for this kind of pathology.