Polymorphisms of FcgammaR have been proposed as genetic factors that influence susceptibility to SLE. FcgammaRIIIB polymorphism in systemic lupus erythematosus (SLE) have been studied in various populations, but the results were inconsistent. The aim of this study was to determine the association of FcgammaRIIIB polymorphism in Korean lupus patients. One-hundred and eighty-three SLE patients (166 female, 17 male) meeting 1982 ACR criteria and 300 Korean disease-free controls were enrolled. Genotyping for the FcgammaRIIIB NA1/NA2 was performed by PCR of genomic DNA using allele-specific primers. There was no significant skewing in the distribution of the three FcgammaRIIIB genotypes, and alleles between SLE and the controls. The frequency of FcgammaRIIIB genotypes in SLE patients and controls was FcgammaRIIIB NA1/NA1 27.9% versus 26%, NA1/NA2 55.2% versus 51.7%, NA2/NA2 16.9% versus 22.3%, respectively. The gene frequencies of NA1 allele were 0.56 in the SLE and 0.52 in controls, respectively. Among clinical manifestations, thrombocytopenia was more common in FcgammaRIIIB NA2/NA2 genotype (P = 0.04, OR 2.4, 95% CI 1.0-5.4), and NA2 allele (P = 0.03, OR 1.7, 95% CI 1.1-2.8). Although FcgammaRIIIB polymorphism was not associated with the development of SLE in Korean, thrombocytopenia was associated with FcgammaRIIIB NA2/NA2 genotype, and NA2 allele.