Erythromycin and colistin (or other thermostable antibiotics) may legally be added to polymethylmethacrylate (PMMA) for use in the fixation of prostheses to bone. The antibiotics are leached or rapidly released from the combination in bactericidal concentrations. They do not reduce the strength characteristics of the cement below acceptable standards, nor do they change its handling characteristics. Erythromycin alone was used in 1112 total hip arthroplasties between 1971 and 1976, with an infection rate of 0.98%. Erythromycin-colistin bone cement was used in 786 total hip arthroplasties from July 1976 to December 1980, with a deep-wound infection rate of 0.4%. Erythromycin-colistin-containing bone cement is safe and effective in treatment of and prophylaxis against deep-wound infection in total joint arthroplasty.