A 13-year-old girl, diagnosed with osteosarcoma, was treated with osteoarticular resection of the right proximal femur followed by reconstruction using an allograft–prosthesis composite. A coronal-T1 (A) magnetic resonance image shows a tumor extension to the proximal meta-diaphyseal region of the right femur. A preoperative anteroposterior radiographic view (B) showing an osteolytic lesion of the proximal femur. (C) Radiograph at one month postoperatively, showing the reconstruction using a press-fit femoral stem and reconstruction of the hip with bipolar hemiarthroplasty. (D) Radiograph at the 1-year follow-up showing fracture of the greater trochanteric region. Allograft–prosthesis composites may help preserve bone stock for future revision surgeries in children with bone sarcoma of the proximal femur.