Vibrio harveyi is known to be a major pathogen in mariculture animal systems.Disease outbreaks attributed toV.harveyi have been reported in main mariculture animal farm production.In recent years,mass mortalities of many cultured kinds of maricultured fishes,such as Litopenaeus vannamei,Pseudosciaena crocea,and Lutjanus sanguineus have occurred frequently infected by V.harveyi. In this article the 101 isolates of V.harveyi were subjected to random amplified polymorphic DNA(RAPD)-PCR and BOX-PCR analysis to investigate the genetic variability among V.harveyi strains.A total of 10 RAPD primers were designed for their specificity in detecting V.harveyi,and only the primer PM2 was highly reproducible and found suitable to use in RAPD-PCR.The genetic diversity among V.harveyi isolates assessed by RAPD-PCR by PM2 primer yielded 15 different RAPD patterns which clustered the isolates into 18 groups at 65% similarity level.Similarly,BOXPCR clustered the 20 patterns into15 groups at 40% similarity.However,with RAPD-PCR and BOX-PCR,101 V.harveyi could be divided into 18 groups at 50% similarity.We could obtain the accurate results of molecular genetic diversity by both RAPD-PCR and BOX-PCR.