Abstract: To reveal isozyme variation of Red Seabream ( Pagrus major) , each 50 index samples of a wild population and of a hatchery population from Haizhou Bay of Yellow Sea were investigated through starch gel electrophoresis. Twenty loci of 13 enzymes were detected. The proportion of polymorphic loci was 45 % and 25 % ( P_0.95) , respectively , ME and EST- b showed the highest genetic variation among the detected loci. The mean heterozygosity ( Ho) in two populations were 0.141 ±0.044 and 0.095 ±0.043 , respectively. The hatchery population possesses lower genetic variation than the wild populations. The relatively small numbers of broodstock may result in the lower genetic variation of hatchery population. For the sustainable development of the mariculture in the future , some appropriate measures , such as enlarging the broodstock number , should be taken in case of the reducing of population genetic variation. The result of isozyme analyzing was compared with that of RAPD technique in this passage , which showed that these two results were identical. So it is meaningful to combine RAPD with isozyme technique in assessing population genetic variation.