Objective To establish a PCR method to dete4ct monkey B virus (BV). Method According to published primers provided by Makoto H, w e used PCR method to amplify BV DNA directly from monkey blood or indirectly from propagated bloo d BV cultured in Vero cells. PCR segments were bound to pGEM-T vector.R esults The primers were able to amplify both blood BV and propagated bl ood BV and give identical results. The amplified segment was sequenced and was 1 00% homologous with E2490 (American BV strain). Conclusion A PC R method has been established to directly detect monkey B virus from blood.