Sarcomatoid carcinoma of prostate has been rarely reported and occasionally difficult to distinguish from a true sarcoma or carcinosarcoma. A case of sarcomatoid carcinoma of the prostate, which has been occured in 61-year-old male patient is presented. The tumor consists of carcinomatous areas with epithelioid cells, sarcomatoid areas with spindle cells and foci of heterologous osteosarcoma component. The phenotypic nature of the tumor was confirmed immunohistochemically by positive reaction for cytokeratin, epithelial membrane antigen, vimentin and prostate specific acid phosphatase in both sarcomatous and carcinomatous components.