We describe our successful operative management of a solitary metastasis in the sternal body after modified left mastectomy. Because the primary lesion was well controlled and the sternal metastasis was isolated, we performed a subtotal sternectomy, with full-thickness resection of the anterior chest wall, including the sternal body and inferior part of the manubrium (14.5 cm x 8.5 cm x 3.0 cm). A prosthesis was created to fill the defect, by sandwiching molded bone cement (methylmethacrylate) between two layers of Prolene mesh. The prosthesis was fixed to the cut ends of the costal cartilages and the residual manubrium. The patient had an uneventful course, and her respirations were normal without paradoxical movement of the thorax or hypoxemia. The skin covering the prosthesis healed well. Thus, the creation of an artificial chest wall from methylmethacrylate and Prolene mesh is a useful technique for repairing sternal defects.