This report addresses the role of antibiotic residues for the development or dissemination of antibiotic resistance in the environment. It summarizes data on fate and occurrence of antibiotics in the environment and gives an overview of the existing information on effects at realistic concentrations. At present, there is too limited information to judge whether antibiotic residues in the environment can exert effects on resistance. However, such effects cannot be ruled out, when additional data on minimum inhibitory and minimum selective concentrations are taken into account. A test system for regulatory purposes is described and the results of an international expert meeting are summarized.