A number of organotin compounds are used in the society, but the knowledge ontheir environmental impact is mainly restricted to those compounds that are used inantifouling paints on ships. In this screening study, the occurrence of butyltins, octyltins, phenyltins and tricyclohexyltin in the Swedish environment was investigated. The sampling programme was setup based on the use of organotins in nonbiocidal applications. There is an emphasis on the lacustrine environment in threeurban regions, but the study also covers sewage treatment plants, an agricultural field, a plastics industry, landfills, foodstuffs and breastmilk. A total of 107 sampleswere analysed. Furthermore, the physical-chemical and toxicological properties oforganotins are briefly summarised and their use in the Swedish society is described.The major goals were to assess‰ If diffuse release of organotins occurs in urban areas‰ If releases of organotins from municipal sewage treatment plants (STPs) influence the levels in the aquatic environment‰ If industrial use may cause a local impact of organotins‰ If the use of sewage sludge as a fertiliser causes organotin accumulation insoils‰ If human exposure is significantBecause this is a screening study, some of these goals had to be assessed on the basis of few samples, whereas other aspects could be more thoroughly investigated.Urban stormwater sludge from three cities shows that diffuse releases of monobutyltin, dibutyltin, tributyltin, monoctyltin and dioctyltin occur in urban areas. This diffuse release is also evident in the aquatic environment, where in particular DBT andMBT are enriched in urban sediments. The relative abundance of organotin compounds is very similar in urban stormwater sludge and sewage sludge, suggestingcommon sources. Furthermore, the specific load to municipal STPs (µg/d/pe) is similar to earlier results from households, suggesting that diffuse releases from products in the urban environment is important.STPs appear to influence the levels of MBT in their recipients moderately, but noother organotin compound is released in significant quantities by these STPs. Theconcentrations in stormwater sludge and soil close to a PVC industry suggest thatemissions may occur from the current industrial use of butyltins and octyltins.Fish from various lakes and the Baltic Sea contain butyltins and phenyltins. Whenconsidering the occurrence of these substances in sediments, and their present use, itappears that phenyltins are more strongly accumulated than butyltins in fish. Perchfrom Mälaren, Stockholm city and the Stockholm archipelago contains higher levelsof dibutyltin, tributyltin and triphenyltin than fish from other lakes. The levels inStockholm city is particularly high.In conclusion, there was a good correspondence between the type of organotin compounds found in the present study and those that are used in the society. Phenyltinsmainly occured in the aquatic environment in areas where large ships travel. Octyltins were found in waste waters and sludge, in urban stormwaters and in certainurban sediments, suggesting an association to products containing octyltins. Butyltins were found in all these environments, in agreement with their use both in themarine environment and in urban areas.