Antineoplastic substances are frequently cancerogenic, mutagenic, fetotoxic and embryotoxic. Some medications are metabolised poorly by patients after administration. At present, only little knowledge is available concerning their behaviour in the environment. Therefore, biodegradation of epirubicin hydrochloride was investigated using the Closed-Bottle-Test (not readily biodegradable). A prolongation of the test up to 62 days did not alter the results. Epirubicin hydrochloride was not found to be toxic against waste water microorganisms. Further investigations about the elimination of epirubicin hydrochloride in the process of waste water treatment and its environmental properties are necessary to obtain more information about the possible risk for man and the environment.