For fish immune defences, cytokines and anti-microbial peptides (lysozyme) in circulating systemplay important roles. In the present study, the effects of Astragalus polysaccharides (APS)injection on gene expression of interleukin 1β (IL-1β), tumor necrosis factorα (TNF-α) andlysozyme-C in the head kidney, gill and spleen of common carp were determined using semiquantitativereverse transcription-polymerase chain reaction (RT-PCR). After injection of APS,IL-1β mRNA level increased in a dose-dependent manner in the head kidney, while no significantchanges were found in the gill and spleen. High dose of APS up regulated TNF-α transcription inthe gill and spleen, while TNF-α mRNA level decreased significantly in the head kidney of lowdose of APS. Lysozyme-C mRNA levels were up regulated in the gill of low dose of APS and spleenof middle dose of APS. No effect of the APS on lysozyme-C expression was observed in headkidney. These results constitute a first step toward the understanding of APS effect on cytokinesand immune-related gene expression in different organs of common carp.