Ten microsatellite primers of Takifugu obscurus and sixteen microsatellite primers of Takifugu rubripes were used to investigate genetic diversity of four T.obscurus populations (one wild population from Changshu,one released population from Yangzhong and two cultured populations from Nantong and Shanghai respectively) in this study.Twenty microsatellite markers were amplified successfully and a total of 113 alleles were detected in the four populations.In these populations the average number of alleles was from 4.95 to 5.50,the value of average observed and expected heterozygosity ranged from 0.686 7 to 0.761 7 and from 0.653 0 to 0.700 0 respectively,and the mean polymorphic information content was from 0.601 3 to 0.638 4.Several loci were found to deviate from Hardy-Weinberg Equilibrium in each population,which indicated that the deficiency of heterozygote existed in the four populations.The value of genetic differentiation coefficient and gene flow were 0.040 6 and 5.905 6 respectively.These results suggested that the four populations have a low level of differentiation and great gene exchange among them.The genetic similarity coefficient of the four populations was from 0.859 0 to 0.915 8 and the genetic distance was from 0.088 0 to 0.151 9.Cluster analysis using the UPGMA method showed that Shanghai population formed an independent cluster and the other three populations formed another cluster.