Following implantation of Gentamycin PMMA beads, the concentration of antibiotics in the wound secretion was investigated in an animal experiment which corresponded to the clinically applied procedure. The measured concentrations of active substance over a period of 6 days were on an average 8 times higher than the maximum serum titers obtainable with systemic application of antibiotics, and consequently they exceeded by several dilution stages the minimum bactericidal concentrations of most of those bacteria which are responsible for infections of wounds and bones. The kinetics of release of Gentamycin out of the PMMA beads are presented, and compared with that of bone cement which contains antibiotics and which is used in endoprostheses. From the results, conclusions about the intraoperative techniques which should be realised have been drawn, conditions which are of decisive importance for the success of this new treatment for infections of the bone and soft tissue.