The extremely toxic antifouling pesticide tributyltin (TBT) was regulated in many countries in the 1980s and 1990s. The regulations have been successful in reducing the toxic threat posed by TBT in many locations around the world. However, there are also many locations at which recovery has not been seen, even 10 years after regulation. Because of continuing concern about the environmental hazards of TBT, the International Maritime Organization proposes to prohibit all antifouling uses of TBT by 2003, and the presence of TBT on ship hulls by 2008. Canada has recently announced a prohibition on the use of organ-otin antifouling paints by January 1, 2003. This article reviews the persistence, bioaccumulation and toxicity of TBT in aquatic environments, and concludes that TBT meets all such criteria for designation as a Track 1 substance under Canada's Toxic Substances Management Policy, necessitating measures to virtually eliminate it from the Canadian environment. Because of the long persistence of TBT in sediment, there may be a "legacy problem" in sediments in some locations in Canada for perhaps 20 to 30 years after a total ban.