Liposarcoma is a rare mesenchymal tumor that occurs most commonly in the soft tissue of the extremities. It develops deeply in the intramuscular fatty tissue and consists of lipoblasts. We experienced a case of well-differentiated liposarcoma on the thigh of a 48-year-old female, who presented with a skin-colored, child fist-sized mass. Liposarcoma is rare in the dermatologic field, so we herein report a case of well-differentiated liposarcoma.(Ann Dermatol (Seoul) 18(2) 105~108, 2006)