We describe a 47-year-old man with a giant cell tumor of bone involving the acetabulum treated with curettage and bone grafting which resulted in good remodeling of the hip joint. The patient had a 15 x 18-cm(2) mass lesion extending from the right ischium to the acetabulum. Treatment included curettage, phenol, and ethanol application as an adjuvant, and cancellous bone allografting was performed on the subchondral area of the acetabulum. The posterior column of the acetabulum was disappeared by tumor invasion. Despite central migration of the femoral head, adequate hip joint repair was achieved without surgery 5.5 years postoperatively and with no tumor recurrence. The patient could walk without pain or ambulation aids; hip range of motion was 100 degrees for flexion, 0 degrees for extension, 30 degrees for abduction, 45 degrees for external rotation, and 10 degrees for internal rotation, and the functional result was 93.3% in the Enneking scoring system. We performed intralesional curettage with phenol and ethanol adjuvant therapy for pelvic giant cell tumor without tumor recurrence, and good repair of a hip joint adaptation can be achieved even in an adult patient.