The aim of this study was to investigate the influence of Killer Immunoglobulin-like Receptor (KIR) gene matching and the relative importance of these genes when identifying potential donors for Haemopoietic Stem Cell Transplantation (HSCT) so that selection may be prioritised where a choice of donors exists. HSCT is used to treat not only haematological malignancies such as leukaemia and lymphoma but also certain solid organ tumours and a small number of immunological disorders.