The impact of transfusion of leucodepleted platelet concentrates (PCs) on cytomegalovirus (CMV) disease was assessed in 215 allogeneic (145 unrelated and 70 related donor) transplants over 3 years. In 43%, both donor and patient were CMV seronegative (CMV-/-). All received CMV-seronegative red cells and random leucodepleted PCs. No CMV disease occurred in any CMV-/- (low risk) transplant. CMV infection occurred in 31 seropositive patients (26%); 13 died and five deaths were attributable to CMV disease. When compared with historical controls, who received CMV-seronegative PCs, we found no difference in transfusion-acquired CMV in the current cohort.