A 74 years-old mole patient visited one OPD with a soft tissue toast in the posterior aspect of the eight thigh, although he had received n removal procedure in the same site in the other hospital. The mass man found 40×10×5cm in size computed tomography (CT), extending form the inferior margin of the gluteus maximus muscle to the middle of biceps femoris, with the sciatic nerve located at the central portion of the mass. At surgery, the nerve was well preserved. And postoperative radiotherapy and chemotherapy followed. After the surgical removal, the mass proved to be moderately differentiated myxoid type of liposarcoma pathologically. In conclusion, basing the experience of the above case, We strongly suggest that a complete surgical removal followed by intensive radiotherapy and chemotherapy is mandatory for a soft tissue liposarcoma to prevent recurrence.