Allograft inflammatory factor-1 (AIF-1) is a cytoplasmic calcium-binding protein involved in inflammatory response-related diseases in mammals. Previously an identified AIF-1 gene was simply reported in yellow grouper. The characterization of AIF-1 gene and its expression at the gene and protein level are further described. Yellow grouper AIF-1 is composed of 147 amino acids, and 64%～84% identical to other homologues. Basal level AIF-1 mRNA expression was noted in spleen, anterior kidney and kidney, using reverse-transcription polymerase chain reaction (RT-PCR). After stimulation of LPS, the AIF-1 mRNA expression was up-regulated in tissues examined: spleen, anterior kidney, kidney, heart and liver, but not in muscle. The recombinant AIF-1 protein was expressed in Escherichia coli, and then purified for the development of antiserum. Western blotting analysis revealed a band with a molecular mass of about 17 ku. Allograft inflammatory factor-1 (AIF-1) is a cytoplasmic calcium-binding protein involved in inflammatory response-related diseases in mammals. Previously an identified AIF-1 gene was simply reported in yellow grouper. The characterization of AIF-1 gene and its Expression at the gene and protein levels are further described. Basal level AIF-1 mRNA expression was noted in spleen, anterior kidney and kidney After stimulation of LPS, the AIF-1 mRNA expression was up-regulated in tissues examined: spleen, anterior kidney, kidney, heart and liver, but not in muscle. The recombinant AIF-1 protein was expressed in Escherichia coli, and then purified for the development of antiserum. Western blotting analysis revealed a band with a molecular mass of about 17 ku.