Abstract: 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.