Recent evidence suggests that certain Fc gamma receptor alleles are genetic risk factors for infectious diseases. In this study, we evaluated Fc gamma RIIa polymorphism in patients with brucellosis. In a case-control study, the frequency of two alleles and three genotypes for Fc gamma RIIa were measured by PCR in 150 patients with brucellosis and 125 healthy controls. The H131 and R131 alleles were found in 133 (44.3%) and 167 patients (47.6%), respectively. The frequencies for the three genotypes (a/a, a/r, r/r) were 10 (6.7%), 113 (75.3%) and 27 (18%), respectively. There was no significant difference in the distribution of Fc gamma RIIa genotypes and the two allelic forms between the patients and controls. Our study indicates that Fc gamma RIIa polymorphism is not decisive for the acquisition of brucellosis.