Background: Brucellosis is the major bacterial zoonoses of global importance caused by Brucella spps. FC γRIIA receptor plays a central role in phagocytosis of IgG2-opsonized bacteria. FC γRIIA exhibits allelic polymorphisms with different capacities for binding IgG2 and phagocytosis. Cells expressing Fc γRIIa-H131, bind more efficiently to complexes of IgG2 than those expressing the Fc γRIIAR131 variant. The purpose of this study was to evaluate the association of FC γRIIA polymorphisms with susceptibility to or severity of brucellosis. Materials and Methods: In this study, we evaluated FC γRIIA polymorphisms (R/R131, R/H131, H/H131) in 67 patients with brucellosis and 67 age, sex and geographical matched healthy volunteers. FC γRIIA genotyping was performed by using a sequence-specific primer polymerase chain reaction (SSP-PCR). Results: The comparison of the FC γRIIA genotypes distribution in patients with brucellosis and controls showed a higher frequency in FC γRIIA-R/R131 homozygosity in patients than controls (47.8% vs. 28.4%). Logistic regression analysis showed that there is a significant correlation between R/R131 genotype and brucellosis (OR=2.3, 95%CI=1.3-4.2, P=0.04). Although the frequency of the FC γRIIA-R/R131 was higher in patients with chronic brucellosis compared with acute brucellosis, we did not find any statistically significant differences (53.8% vs. 46.3%, P=0.65). Conclusion: The result of this study showed that the homozygous genotype of FC γRIIA-R/R131 in patients with brucellosis may be associated with susceptibility to brucellosis as a genetic risk factor.