Abstract: In order to determine the immune regulatory effect of bursin on avian influenza (H9N2) vaccine, two hundred 13-day-old chicken were randomly divided into four groups. One was for the control, the others for vaccine, vaccine plus bursin and bursin treatments respectively. The change of average index of bursa of fabricius and spleen and serum antibody titer in chicken were examined by means of hemagglutination inhibition test every 7 days from the 13th day after treatment. The results showed that bursin could enhance chicken serum antibody titer on avian influenza (H9N2) oil adjuvant inactivated vaccine and develop bursa of fabricius significantly. Bursin also could prolong the maintenance of high serum antibody titer in chicken. It was suggested that bursin could improve immune effects of avian influenza (H9N2) oil adjuvant inactivated vaccine in chicken．

Key words: bursin, avian influenza (H9N2) vaccine, average index of bursa of fabricius, average index of spleen, AIV antibody titer