The aim of this study was to investigate the role of FcgammaRIIB gene in susceptibility to systemic lupus erythematosus (SLE) using family-based association methods. In total, 119 patients with SLE from 95 nuclear families, aged from 14 to 78 years, who met the American College of Rheumatology (ACR) 1997 criteria, were recruited, as were 316 family members of these patients. A family-based association analysis was used to explore the relationship between gene polymorphism and SLE. We studied three single-nucleotide polymorphisms (SNPs, rs10917661, rs5017567, and rs1050499) encoding non-synonymous substitution in the FcgammaRIIB gene with respect to genetic susceptibility to SLE in collection of 435 subjects from 95 nuclear families. We performed the genotyping using PCR-restriction fragment length polymorphism method. Among 119 SLE patients, the frequencies of FcgammaRIIB Gln/Gln,Gln/Ter and Ter/Ter genotypes were 12.7, 60.7 and 26.6%. Univariate (single-marker) family-based association tests (FBATs) demonstrated that variant alleles at a SNP, rs10917661, in exon 2 of FcgammaRIIB gene were significantly associated with genetic susceptibility to SLE in additive model (exon 2, Z = 3.444, P = 0.00057). transmission/disequilibrium test (TDT) and sibship disequilibuium test (SDT) analysis showed an excess of the alleles of 50Ter from heterozygous parents to affected offspring (chi(2) = 10.88, P = 0.0013). However, the rs5017567 and rs1050499 SNPs were not found in Chinese population. Our findings provide strong evidence suggesting that a FcgammaRIIB-Gln50Ter loci might be the susceptible factor of SLE in Chinese population.