Following the increasing interest about the possible role of hospital and municipial wastewater systems as one hot spot for the selection of antibiotica resistant bacteria, biofilms were investigated concerning enterococci, staphylococci, Enterobacteriaceae and heterotrophic bacteria. Apart from wastewater, biofilms were also investigated in drinking water from embankment filtrate to estimate the occurrence of resistant bacteria and their resistance genes in order to indicate a passage from wastewater and surface water to the drinking water distribution net. Vancomycin resistant enterococci, which were most frequently found in wastewater biofilms, were characterized by antibiograms. The vanA resistance gene was detected by molecular biological methods such as PCR. Besides in wastewater biofilms the vanA gene was detected in drinking water biofilms in absence of enterococci indicating a possible gene transfer to autochthonous drinking water bacteria. The mecA gene coding for methicillin resistance in staphylococci was detected in hospital wastewater biofilms, but not in other compartments. Enterobacterial ampC resistance genes coding for beta-lactamase activities were amplified by PCR from wastewater, surface water and drinking water biofilms. In addition conventional techniques for determination of the resistance situation concerning further clinical relevant antibiotics were used. Here, a high percentage of resistant bacteria was isolated from hospital and municipal treatment plant wastewater biofilms. A question to be raised is the spreading of resistance both in aqueous medium, as well as in human organisms after water consumption. Includes 15 references, tables, figures.