The occurrence of butyltin compounds in the seawater and sediment of Masan Bay was investigated. The concentrations were in the range of $ND-0.059{mu}g/ell$ for tributyltin (TBT), $ND-0.091{mu}g/ell$ for dibutyltin (DBT) and $ND-0.720{mu}g/ell$ for monobutyltin (MBT) in the seawater, and $ND-0.233{mu}g;TBT/g.dry$, $ND-0.197{mu}g-DBT/g.dry$ and $ND-0.684{mu}g-MBT/g.dry$ in the sediment. Among the butyltin compounds, the major component in the seawater was MBT, while the predominant species in the sediment changed with time. The tributyltin concentrations in the sediment are approximately three orders of magnitude greater than the associated water column levels. Sediment/water partition coefficients (K) of TBT were between $0.6 imes10^3;and;5.0 imes10^3$.