Short core sediment samples were collected from the tidal flats on the southwestern coast of the Korean Peninsula in 2001 to evaluate the background geochemical compositions of Korean cratonic sediments. Sediment samples from twelve cores collected in Sihwa, Semangun and Mokpo (excluding one core from Mokupo harbor) show quite homogeneous compositions. Their composition is characterized by similarity to average UCC values with enrichment of Cr and V and depletion of Cu, Sr, Ca and P. These Korean tidal flat sediments have quite similar compositions to reported geochemical compositions of southwestern Yellow Sea sediments. These data are useful as bench marks for assessments of the coastal environment.13;