Genetic distance and the relationships among 15 species of generaTrachurus, Decapterus,Selar, andSelaroides were estimated from 18 electrophoretically detectable isozyme genes. Estimates of genetic distance (D) between every pair of species within the genusTrachurus ranged from 0.005 to 0.560 with a mean of 0.322, and from 0.484 to 1.868 with a mean of 1.022 within the genusDecapterus. Between species of different genera, estimates of D ranged from 0.786 to 2.863 with a mean of 1.784. From these results,Decapterus species could be considered as having evolved over a long period whileTrachurus is a newly arisen genus. A relationship among species suggests that theDecapterus species are expanded to offshore and deep area after being divided into some groups, and that theTrachurus species are divided presumably into at least two groups, one group of which is coastal and the other of which is offshore.Trachurus japonicus andTrachurus novaezelandiae could be considered subspecies on the basis of allelic distribution and genetic distance.