A series of 13 chest wall resections for recurrent breast tumours are reported, the defects being closed by synthetic prostheses. In nine patients the prostheses were covered by a latissimus dorsi flap, while in the last eight patients a rigid 'shield' prosthesis of methyl methacrylate was used, and a stable chest obtained. Mechanical ventilation for more than 24 h was not required in those patients in whom a shield was used.