Abstract: It remains to be confirmed that waterborne tributyltin,similar to Hg2+,Cd2+ and Mn2+,can enter nerves innervating water-exposed sensory organs of fish and were transported to the brain by axonal transport.The authors exposed rainbow trout(Oncorhynchus mykiss)to waterborne ()113Sn-TBT(4.2 kBq/L) with another group of fish received an intravenous injection of ()113Sn-TBT.Distribution of ()113Sn-TBT in the bodies of fish was visualized and quantified by quantitative whole-body autography.The results show that ()113Sn-TBT can be taken up in different water-exposed sensory nerve terminals such as eminentia(lateral lines organs) and transported directly to the brain by axonal transport.Labeling of the brain was also seen for i.v.-injected fish,indicating that the blood-brain barrier is not impervious to TBT.It is concluded that TBT can be accumulated in fish brain by the transfer water→gills→blood stream→blood-brain barrier→brain,and TBT can be taken up in the fish bodies through different water-exposed sensory nerve terminals and transported to the brain by axonal transport.