UV-absorbing organic chemicals (UV filters) are being increasingly used in sunscreens, personal care products and in the protection of materials against UV irradiation. Environmental contamination originates from direct input from recreational activities and wastewaters. Concentrations in treated wastewaters are in the lower μg/l range, whereas in rivers and lakes they are in the range of a few up to hundreds of ng/l. It is known that lipophilic UV filters accumulate in aquatic biota, but only little is known about their environmental fate. A large number of UV filters elicit hormonal effects in vitro. Estrogenic activity has also been demonstrated for some UV filters in fish in vivo. Benzophenone-1 (BP1), benzophenone-2 (BP2), 3-benzylidene camphor (3BC) and ethyl-4-aminobenzoate (Et-PABA) lead to induction of vitellogenin. 3BC and BP2 cause feminization in secondary sex characteristics of male fish, alteration of gonads in male and female fish and decrease in fertility and reproduction. The lowest observed effect concentrations for 3BC and BP2 were 3 μg/l and 1.2 mg/l, respectively. UV filter mixtures show mainly a synergistic activity in vitro, whether this is also reflected by the in vivo activity is under investigation. In conclusion, a hazard and risk for aquatic ecosystems cannot be ruled out for the UV filter 3BC, where histological and reproductive effects occurred in fish at low concentrations. However for BP1, BP2 and Et-PABA an environmental risk is rather low based on current knowledge.