Malignant mixed Müllerian tumors (MMMTs) are highly aggressive neoplasms composed of sarcomatous and carcinomatous elements commonly encountered in the female genital tract and rarely occur in extragenital sites. Most of extragenital MMMTs develop from the peritoneum. To our knowledge, only 25 cases have been described in the literature. Among them, only 2 cases have arised in the major omentum.1 Here we report a case of a 67-year-old female with primary MMMT of the major omentum.