BACKGROUND: The topical application of Vancomycin is increasingly being used in orthopedics because of the development of methicillin resistant bacteria. Consequently, resistance to Vancomycin has recently been on the rise. One possible explanation for this phenomenon could be the thermal degradation of Vancomycin to antibacterially inactive crystalline degradation products (CDP-1s). The aim of our in vitro experiment was to compare the creation and elution characteristics of CDP-1s and the active form of Vancomycin (factor B) released from bone grafts. METHODS: CDP-1s and the factor B released from bone grafts into the buffer solution were measured using the high-performance liquid chromatography method at progressive intervals. RESULTS: The factor B was released from bone grafts at the highest levels, typically on the first day (618.8 mg/L). CDP-1 levels kept increasing until the end of measurement on day 15, when the concentration of CDP-1s (1280.7 mg/L) was much higher compared to that of factor B (217.5 mg/L). CONCLUSIONS: We confirmed the tendency of Vancomycin to convert to antimicrobially ineffective CDP-1s. Although Vancomycin is decomposed into crystalline degradation products, its active forms are released from bone grafts in sufficient concentration for more than two keks (Tab. 3, Fig. 1, Ref. 15).