The uptake of tributyltin (TBT) in caged Dreissena polymorpha was investigated in a freshwater marina contaminated with TBT released from antifouhng paints Depuration was followed on bivalves transferred from the marina, where they live naturally, to a location without organotin contamination The butyltin concentration of the mussel tissues and the water was determined and the growth of the mollusks followed during 105 d The accumulation was extremely rapid, reaching a threshold of 63 μg/g dry weight after 35 d with a very high BCF of 900,000 No effect on growth or mortality was observed The elimination experiment showed a half life of 26 d without reaching a steady state after 105 d The mean ambient TBT water concentrations were 70 and 4 ng/L during the uptake and depuration experiments, respectively Rate constants have been cal culated The growth rate of the eliminating Dreissena polymorpha was half as high as the rate of the accumulating mussels and of those caged in the site with low TBT concentrations serving as reference The bivalves living naturally in the marina might have been affected during their larval or juvenile stages, resulting in a reduced growth rate of the adults, which remained diminished even when transferred to an area remote from known TBT sources