To study the genotype distribution and the effects of killer immunoglobulin-like receptors (KIR) and human leukocyte antigen (HLA) class I ligand on related donor hematopoietic stem cell transplantation (HSCT).The genotypes of donor/recipient HLA-Cw and donor KIR were determined by polymerase chain reaction-sequence specific primer (PCR-SSP) in 87 cases of related donor HSCT (40 cases were haploidentical HSCT, and the remaining 47 cases were HLA-identical sibling HSCT).All the donors possessed KIR2DL1, 2DL2/L3, 2DL4, 3DL2, and 3DL3, and 96.6% of donors possessed 3DL1. The rate of activating KIRs varied. 97.7% of the recipients expressed C1, while the rates of C2, Bw4, and HLA-A3/A11 were different. In haploidentical HSCT, KIR-HLA-mismatched group included 34 cases and the matched group included 6 cases. HLA-HLA-mismatched group included 31 cases and the matched group included 9 cases. In matched sibling donor HSCT, KIR-HLA-mismatched group included 42 cases and the matched group included 5 cases. KIR-HLA-mismatched group had higher 2-year disease-free survival (DFS) rate compared with KIR-HLA-matched group [ (71.5 +/- 6.5 ) % vs. (50.0 +/- 10.7)%, P < 0.05].The rate of activating KIR is lower than inhibitory KIRs. Inhibitory KIR2DL1, 3DL1, and 3DL2 may play key roles in the natural killer cell alloreactivity. The DFS rate is higher in KIR-HLA-mismatched group than in KIR-HLA-matched group in related donor HSCT.