Although organotins are notorious man-made organometallic species introduced into the aquatic environment, no investigation had been concerned with contamination of higher trophic animals such as marine mammals until the last few years. Our recent work demonstrated the detection of butyltin compounds (BTCs), including mono-(MBT), di-(DBT), and tri-butyltin (TBT) in marine mammals. This paper reviews BTC contamination in higher trophic animals, based on our recent publications. Analysis for BTCs showed significant accumulation in tissues and organs of three finless porpoises (Neophocaena phocaenoides) collected from Japanese coastal waters. More than 10 g of butyltin ions per gram on a wet weight basis were detected in the liver of a porpoise collected in the semi-closed sea. Distribution of BTCs in the tissues and organs of the porpoises showed a similar pattern to several other marine mammal species: higher concentrations in liver and kidney, and lower in muscle and blubber. In addition, tissues and organs from two water birds and one sea turtle species were also analyzed for BTCs, and their concentrations and compositions were compared among the species. The results showed that the distribution of these contaminants extends widely, not only to marine mammals but also to other higher trophic species. On the other hand, the composition of the BTCs exhibited a specific profile in each species. The ratios of hepatic concentrations of DBT or MBT to TBT for marine mammals were relatively lower than those of water birds and the sea turtle, indicating that metabolism and excretion of TBT may be less efficient in the mammalian species.