From September 1986 to September 1988 a total of 72 patients were treated with collagen gentamicin as a local adjuvant antibiotic therapy. This new carrier system was evaluated with reference to clinical follow-up examinations, pharmacokinetics, bacteriology, immunology and histology. Among 58 cases of osteomyelitis we observed 4 reinfections (6.9%) within the first 3 months, while 54 patients remained free of reinfections over this period and 29 for longer than 1 year. Concerning bacterial pathogens we found an unusually high rate of gentamicin-resistant Staphylococcus aureus strains (28.2%). In 26 cases the gentamicin level was measured in the exsudate and in the urine over a period of 5 days. Consideration of the histology and the pharmacokinetics revealed a direct correlation with the local flow. The collagenous sponge can be resorbed within days, but it can take some weeks. In all cases a very high initial rate of released gentamicin was observed, which was absolutely bactericidal even to resistant strains. Further advantages of the system are the resorbability of the carrier, the simple handling, and the fact that the likelihood of inadequate gentamicin concentrations is excluded.