Primary tumors of lung and breast represent the most frequent cause of neoplastic involvement of the thoracic wall, being primary parietal neoplasms extremely rare; metastatic lesions of the thoracic wall are not an infrequent finding, but represent just an occasional indication for surgery. Prosthetic reconstruction after a resection that includes the bony structures of the thoracic cage is dependent upon the extension of the parietal excision. We report a personal experience with 11 cases of prosthetic reconstruction of the thoracic wall out of a total of 54 extended resections accomplished between 1979 and 1990. We did not find prosthetic reconstruction indicated for thoracic wall defects smaller than 5 cm in diameter, wherever located. As regards larger parietal defects, a reconstructive procedure appeared always necessary for anterior or lateral regions of the thorax, while we never used prosthetic implants for posterior defects, regardless of their size. In all cases we used a Silastic sheet, 1.016 mm thick, reinforced by Dacron mesh, whose margins were molded on the form of the thoracic defect and secured by 2/0 Prolene suture. Follow up ranged from 6 to 36 months. No case of rejection has been observed up to date and no interference with radiation treatment or chemotherapy has been reported.