Heavy metal level and distribution in sediment and bivalves from the tidal flats along the mid-western coast, Korea. were investigated in this study. The averages of heavy metal concentrations in sediments from 5 sampling sites ranged from 86.35-187.77mg/kg for Mn. 13.25-17.73mg/kg for Zn.6.80-11.85mg/kg for Cr,4.28-6.25mg/kg for Ni, 1.85-3.09mg/kg for Cu, 0.004-0.02()mg/kg for Cd and 5.70-10.41 mg/kg for Pb, respectively. From the results of heavy metal concentrations in mussels, the levels of Mn and Fe concentrations in S. strictus collected from S1 antral S2 sites were particularly high. Deviations of heavy metal concentrations am(Ing the individual mussels from the same site could be largely minimized by selecting mussel samples of the limited range in body size(8.5-11cm). Among the mussels of the limited body size, heavy metal concentrations both in the flesh and in the whole soft part were not strongly related to the body size. It was shown that ,in S. strictus, Cu moves fast into the flesh parts after absorption, while Pb and Fe move fast into the non-flesh parts. Overally. the heavy metal concentration in the tends to increase with that in the whole soft parts. The concentration factors(heavy metal concentration in 5. strictus/heavy metal concentration in sediment) showed that, of the examined meta1s. Cd is the most cumulative in the body of S. strictus followed by Zn and Cu, while Mn, Cr. Ni and Pb are not cumulative.