Dibutyltin compounds (DBTC) in polyvinyl chloride resin (PVC) were examined by capillary gas chromatography using a flame photometric detector (FPD). DBTC was extracted with a carbon tetrachloride-methanol (2:1) mixture under reflux. The extract was mixed with a hydrobromic acid solution. Dibutyltin dibromide was converted to dibutyldipentyltin (DBDPeT) by the Grignard reaction with pentylmagnessium bromide and then subjected to gas chromatography. A linear correlation between the amount of tin and peak height was observed in the range of 7.8 to 250 pg of tin on log-log paper. Recoveries of DBTC added to PVC were 92.6-108.1%. The results show that this procedure is more useful and sensitive (the detection limit is 3-4 pg, as tin) than previous methods reported.