Sarcomatoid carcinomas are rare malignancies composed of epithelial (carcinomatous) and sarcomatous elements. High-grade carcinoma is difficult to diagnose by light optic and immunohistochemical studies. The authors give the data available in the literature on sarcomatoid carcinoma of the thymus and also describe their own observation. Its histological pattern is represented by a combination of carcinomatous and sarcomatous elements with extensive necrotic foci. Immunohistologically, the tumor cells expressed total cytokeratin (AE1/AE3), CD99, and focally epithelial membrane antigen. Some tumor cells were vimentin- and SMA-positive. Markers, such as chromogranin A, bcl-2, bcl-6, S-100 protein and myogenin, were negative.