Infectious pancreatic necrosis (IPN) virus, the etiologic agent of infectious pancreatic necrosis in salmonid fish, causes significant losses to the aquaculture industry. The gene for the viral inner capsid protein (VP3) was amplified by RTPCR method from IPNV, and cloned into pET30b vector. The expression of recombinant plasmid pET30bVP3 in E.coli BL21(DE3) was induced and detected by SDSPAGE analysis. The predicted molecular weight for unmodified rtrunc VP3 was approximately 30 ku and this was found to be the case for E.coli protein. The amount of expression made up 30 percent of the bacteria protein total expression by thin layer scanning analysis. The results showed that the VP3 gene of IPNV can express successfully in E.coli BL21. The fusion protein was purified with ProBond^TM resin from the suspension centrifuged and the antisera against VP3 protein was produced. The pET30bVP3 fusion protein can be recognized by the positive serum of IPNV by Western-blotting analysis. The prepared antisera reacted specifically with IPNV antigen by indirect ELISA. The antisera against VP3 protein had OD values at least twice that obtained for the negative control serum at a dilution of 1∶25 600. The results showed that the expressed VP3 protein was immunogenical and antigenical which is the same as the natural IPNV VP3 protein. In this experiment the IPNV VP3 protein was expressed successfully by using prokaryotic expression system. The expressed fusion protein was active and the antisera against VP3 protein were produced.