Carcinosarcoma (true malignant mixed tumor) of salivary gland is a rare neoplasm that demonstrates malignant epithelial and stromal components. We reported a case of carcinosarcoma that showed both adenocarcinoma and osteosarcoma with a large component of osteoclast-like giant cells which localized in the submandibular salivary gland. Histopathologic evidence of pleomorphic adenoma can not be demonstrated in this case. Carcinomatous areas stained with anti-keratin and S-100 antibodies while sarcomatous areas stained with anti-actin, S-l00 and vimentin antibodies. These staining features supplemented the idea of myoepithelial origin of these tumors. We compared the morphologic and immunhistochemical staining features of our case with literature and tried to find further insights into the histogenesis of the carcinosarcoma of the salivary glands.