Transplantation using donors with KIR B haplotypes improves overall survival. The univariate Kaplan-Meier curves for overall survival (OS) are shown for patients receiving transplants from donors with (KIR B/x; n = 317) or without (KIR A/A; n = 131) KIR B haplotypes. Survival is significantly better if the donor had a KIR B haplotype (31% [95% CI: 26-36] vs 20% [95% CI: 13-27]; P = .007).