An animal model of bone infection was designed for evaluation of the benefits of adding antibiotics to polymethylmethacrylate (PMMA) cement. Femora of New Zealand albino rabbits were exposed at the knee; the medullary canals were entered and the contents aspirated. A known number of bacteria was added to each femur before it was filled with either normal Surgical Simplex P bone cement or Surgical Simplex P antibiotic bone cement. The presence or absence of bone infection was documented by quantitative bacteriologic, roentgenographic, and histologic techniques. Simplex antibiotic bone cement prevented infection, even in the presence of 10(7) bacteria. The effectiveness of the antibiotic bone cement was correlated with the rapid release of high levels of erythromycin (14.1 micrograms/g) and colistin (11.3 micrograms/g) specifically at the site of bacterial contamination.