Malignant mixed müllerian tumors (MMMT) are unusual neoplasms occurring mostly in the uterus. In the ovary, they are very rare and represent fewer than 1% of all ovarian malignancies; in the salpinx, they are even rarer than those of the ovary. We report a carcinosarcoma of the left adnexa having features of neuroendocrine differentiation in a 69-year-old female. The tumor contained both adenocarcinoma and squamous cell carcinoma having dear cell change admixed with an undifferentiated malignant mesenchymal component. The sarcoma components consisted of spindle cells, small-round cells and bizarre giant cells mimicking rhabdomyoblast. Almost all of the carcinomatous glandular components and some foci of the squamous cell and undifferentiated carcinomatous components were focal positive for S-100 protein, chromogranin, neuron specific enolase, synaptophysin and Leu-7. Electron microscopy revealed membrane-bound neurosecretory granules in the cytoplasm of some glandular epithelial cells. Histologically, the tumor involved the left adnexa, abdominal peritoneum, surface of the bladder dome, omentum and left external iliac lymph node (stage IIIc).