Acute graft-versus-host disease (GVHD) is the most important complication of allogeneic haemopoietic stem cell transplantation (HSCT), increasing susceptibility to haemorrhage and risk of early mortality. We evaluated 807 allogeneic HSCT patients to assess both the association between bleeding and GVHD, and the influence of haemorrhagic complications on clinical outcome. Up to 55% of patients with grade III-IV GVHD experienced bleeding, compared with 23% of patients with grades 0-l. Furthermore, 45% of patients receiving non-HLA-identical transplants suffered haemorrhage, whereas only 23% of patients receiving transplants from HLA-identical donors experienced bleeding. This can be explained by the higher incidence of severe GVHD among recipients of non-HLA-identical transplants. Our findings also demonstrated that haemorrhagic complications--particularly bleeding from the GI tract--markedly increase patient mortality. An ongoing, multi-centre, randomised, double-blind trial is currently investigating the efficacy and safety of recombinant factor VIIa (rFVIIa; NovoSeven) in the treatment of HSCT-associated bleeding. The trial will examine the ability of three dose levels of rFVIIa to reduce--or even eliminate entirely--the incidence and severity of haemorrhage following such procedures. A total enrollment of 100 patients is anticipated, and preliminary data are expected at the end of 2003.