The antimicrobial activities of calcium-deficient apatite loaded with different concentrations (25, 100, and 500 microg/mg) of vancomycin as a filling biomaterial were evaluated in a methicillin-resistant Staphylococcus aureus (MRSA) rabbit acute osteomyelitis model. Bacterial counts in bone, bone marrow, and joint fluid samples treated with forms of the apatite were compared to those in tissue samples receiving a constant intravenous vancomycin infusion after 4 days. This study demonstrates that using a calcium-deficient apatite loaded with vancomycin dramatically decreases the bacterial counts in bone and marrow.