Trawl surveys were conducted to identify the structure and distribution of the benthic shrimp assemblages related to water masses in the East China Sea and the Yellow Sea in summer (mid-August to mid -October 1989) and winter (January to February 1991). Using cluster analysis,ˆve spatially distinct clusters were identiˆed in the species composition and abiotic data in these seas. Canonical correspondence analysis also suggested a signiˆcant relationship between benthic shrimp species and abiotic factors. The benthic shrimp assemblages in this region consisted of the followingˆve assemblage groups: a group in the Yellow Sea cold water mass; a group originating from the Kuroshio; a group on the continental shelf edge in the Kuroshio water mass; a group in the low-salinity water mass; and a group in the mixed water mass. Water masses appear to be major factors regulating the distribution of the benthic shrimp assemblages in the East China Sea and the Yellow Sea.