Objective To investigate the function of interferon-induced transmembrane protein 3 ( IFITM3) and determine the mechanism by which IFITM3 restricts viruses in African green monkeys (AGMs), IFITM3 was cloned from organs of AGMs, and IFITM3 cDNA and protein expression levels was analyzed. Methods RT-PCR was employed to clone the full-length cDNA from the heart, lung, liver, kidney, brain, lymphoid system, and skin. IFITM3 gene expression was analyzed in different organs by RT-PCR, and data were calculated with DNAman software. Additionally, the location of IFITM3 protein was investigated using pathology and immunohistochemistry assays. Results The IFITM3 gene was found in several cells and organs, including lymphocytes, skin, heart, brain, liver, kidney, lung and spleen. The IFITM3 cDNA was almost 440 bp (442~ 448 bp) and shared 93% homogeneity with Macaca mulatta. Predictive analysis of the IFITM3 protein of AGMs indicated that the protein contained five transmembrane domains and several highly conserved specific sites. The highest expression of the IFITM3 gene was observed in the spleen, and the lowest expression level was found in the brain according to RT-PCR detection. However, a high level of IFITM3 protein was found in the spleen and lymphocytes in immunohistochemistry experiments. Conclusions Based on the comprehensive expression of IFITM3 in AGM organs, especially in the spleen and lymphocytes, IFITM3 may be involved in the immunological response of AGMs and may have an important anti-viral function