Inhibitory KIR haplotype No. 1 (P = 0.006, OR (95%CI) = 0.67(0.50–0.89)), inhibitory KIR haplotype No. 7 (P = 0.001, OR (95%CI) = 0.07(0.01–0.58)) and activating KIR haplotype No. 9 (P = 0.009, OR(95%CI) = 0.282(0.102–0.777)) are protective against RA and inhibitory KIR No. 6 (P<0.001, OR(95%CI) = 16.47(2.18–124.36)) potently increases the risk of RA. The gene discussed is KIR3DL1; the disease is rheumatoid arthritis.