This "in-vitro"-study is concerned with the efficiency of antibacterial agents used in packings after tympanoplasties. For this purpose, gel-foam-material was impregnated either with rolitetracyclin (mostly used in German ENT-clinics), or comparatively with a combination of bacitracin and neomycin or with antiseptics like phenylmercuriborate and povidon-iodine. It is tested, how these impregnated "packings" behave in the presence of pathogenic germs (Staph. aureus, Ps. aeruginosa). Antibacterial effects and alterations of the material were judged. It is shown, that in some regards the rolitetracyclin - very successful in clinical use - is superior to the other substances tested.