The survival benefit of a donor KIR B haplotype is not dependent on the presence of KIR2DS2. Donors with KIR B haplotypes were divided into 2 groups based on the presence (2DS2+, n = 252) or absence (2DS2−, n = 65) of KIR2DS2. Survival was significantly better for patients who received transplants from donors with either KIR B haplotype (2DS2+: 31% [95% CI: 25-37] or 2DS2−: 31% [95% CI: 20-42]) versus donors homozygous for the A haplotype (A/A: 20% [95% CI: 13-27]; P = .02).