Comparative studies of specres dive rsity indices in marine benthiccommunities were maed from pollution surcvey data in the upper gukf of thailand from 1994-1976.the areas compared were the northweslern coastline form samut sakhon province to petchaburi province (area a),the northdastern coastline from sanut prakan province,ko sichang to laem csabamg in chonburi province (area b),the western coastline form area a on down to hua hin in prachuap airi khan province (area c) and the eastern coastline form area b to ko juang in rayong province (area d) the average species diversity index in the northwestern coastliea was found to be lowest at 0.379.