There is evidence of widespread recovery of dogwhelks, Nucella lapillus (L.), from imposer in the North Sea and the Clyde Sea since the introduction of regulations prohibiting the use of TBT-based anti-foulants on vessels less than 25 m in length. The species has become locally extinct in some areas, apparently due to earlier high levels of contamination, but RPSIs have declined dramatically in surviving populations. Individuals were numerous and breeding successfully on most shores visited. Centres of commercial shipping activity are still hot-spots of TBT contamination, but serious impact is surprisingly local. (C) 1996 Elsevier Science Ltd