We have experienced a case of primary thymic carcinoma. A 39 year old female patient admitted with incidentally detected mediastinal mass on chest film.The tumor showed invasion to surrounding tissues and the mediastinal lymphadenopathies were also noted. Invasion to contiguous mediastinal structures made complete surgical extirplation impossible and the biposy findings revealed primary thymic carcinoma. Primary thymic carcinoma is a rare neoplasm originating from the thymic epithelial cells. Clinical behavior of the thymic carcinoma is much different from it`s benign counterpart and several pathologic variants were reported.