Malignant tumors arising from tendon and aponeurosis are very rare. Among those reported most have been interpreted as synovial sarcoma or fibrosarcoma until Enzinger in 1965 described a new type which he called “Clear Cell Sarcoma of Tendon and Aponeurosis”. The tumor has a uniform and distinctive clinical and morphological pattern which distinguishes it from other groups of tenosynovial tumors. The problem of its histogenesis remains, especially its relation to synovial sarcoma. In this paper, we reported one case which is believed to be “Clear Sarcoma in the thigh”.