Concentrations of tributyltin (TBT) and its degradation products, monobutyltin (MBT)and dibutyltin (DBT), were determined in the liver and kidney of striped dolphins ( Stenella coeruleoalba), bottlenose dolphins ( Tursiops truncatus) and in a fetus of the common dolphin (Delphinus delphi) found stranded along the western Italian and Greek coasts in the period 1992-1994. Butyltin (BT) compounds were detected in almost all the samples analyzed and were higher in the kidney than in the liver. Total BT concentrations were 0.78-8.05 mg g À1 wet wt in kidney and 0.015-1.02 mg g À1 wet wt in liver of S. coeruloealba. Bottlenose dolphins had lower BT concentrations than striped dolphins. Although only one fetal sample was analyzed, it showed the highest BT concentrations of all. Unlike BT concentrations in the other adult dolphins, in the pregnant dolphin they were higher in the liver (4.35 mg g À1 wet wt), suggesting that BTs are transferred from mother to fetus. No significant differences in BT concentrations were found between sexes. Of the breakdown products, DBT was predominant in most liver samples and MBT was more abundant in kidney. Although BT concentrations are known to be found in cetaceans inhabiting waters of developed countries, our observations strongly suggest that concentrations found in S. coeruleoalba were either similar to or higher than those reported for other Stenella species collected from coastal areas close to harbors or marinas.