Abstract: In order to study the role of anisodamine as an adjuvant in the immersion administration together with inactivated whole cell vaccines, gibel carps were administrated by immersion with inactivated Aeromonas hydrophila vaccine(inactivated Ah vaccine)with anisodamine on days 1 and 7. Spleens were sampled on days 2, 4, 7, 11, 14 and 21 after the second immersion immunization, and the expression levels of IgM, IL-1β, C3, C-lectin and lysozyme mRNAs in spleen were detected through the real-time fluorescence quantitative PCR(RT-PCR). The gibel carps from the control and immunization groups were challenged intraperitoneally with A. hydrophila YYK090901 at the dose of LD₅₀ concentration on day 21 and then mortality was determined and relative percent survival(RPS)was calculated. The results showed that the expression levels of IgM and IL-1β mRNAs of anisodamine-adjuvant vaccine group reached the peak on day 4,i.e. 28. 3 and 332. 7 respectively, but the adjuvant-free vaccine group reached the peak on day 11. The expression levels of C3, C-lectin and lysozyme mRNAs of the anisodamine-adjuvant vaccine group were significantly higher than those of the adjuvant-free group and the control, and those of the anisodamine-adjuvant group had longer expression duration than the others. The efficacy of inactivated Ah vaccine could be significantly improved by anisodamine through immersion administration, and RPS rate was 80. 0%. The results showed that anisodamine immersion administrated gibel carps together with inactivated whole cell vaccines can significantly promote the expresstion of IgM, IL-1β, C3, C-lectin and lysozyme mRNAs in spleen, and protect gibel carps better against A. hydrophila infection.