The objective of this study was to investigate the putative association of KIRs, HLA class I ligands, and KIR/ligand combinations with rates of development of acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), and chronic myeloid leukemia (CML). This evidence concerns the gene KIR3DL1 and chronic myelogenous leukemia, BCR-ABL1 positive.