Biological test assays play an important role for estimating the effects of herbicides on non-target organisms. Up to now there are only few test methods to investigate these effects on aquatic ecosystems in standardized tests. In this study the effects of three commonly used herbicides on Lemna minor, Lemna trisulca, Spirodela polyrrhiza, Myriophyllum spicatum and Ceratophyllum demersum were examined with respect to four different end-points.