Myeloid leukemia patients (n=113) of AA KIR genotype that receive a transplant from a donor with a Bx KIR genotype (BB or AB) have poorest overall survival. Kaplan-Meier analysis of overall survival for patients with the donor-recipient KIR genotype combinations: (i) donor-AA/recipient-AA (n=8/21), (ii) donor-AA/recipient-Bx (n=3/10), (iii) donor-Bx/recipient-AA (n=9/11), and (iv) donor-Bx/recipient-Bx (n=29/71). The equality of all four curves was tested (d.f.=3, p=0.05). Pairwise comparisons of the curves was then performed by Cox proportional hazard modeling, where the overall type I error rate was controlled by the initial test. Comparison of survival between patients with donor-AA/recipient-Bx and: donor-AA/recipient-AA (p=0.59); donor-Bx/recipient-AA (p=0.046; hazard ratio=3.8, 95% CI=1.02-5.45); and donor-Bx/recipient-Bx (p=0.5). KIR genotype ‘Bx’ indicates that the individual has at least one ‘B’ haplotype; the second haplotype can either be an ‘A’ or ‘B’. The (n=) refers to the number of patients in each respective group who experienced the clinical endpoint being analyzed.