Sixty-seven consecutive patients with aplastic anemia or leukemia who had been treated by allogeneic marrow transplantation and had survived for more than 1 month were surveyed in order to determine the incidence of nonviral infections occurring from 1 month to 3 years after transplantation. Twenty-eight of the 67 patients had one or more infections during this period. Around 20% suffered from pulmonary infections and 20% were classified as having a systemic infection. Ten patients died of bacterial or fungal infection, of whom 6 had graft-versus-host disease. In multivariate analyses acute graft-versus-host disease (P less than 0.0009), splenectomy (P less than 0.02), cytomegalovirus infection (P less than 0.05), and a low marrow cell dose (P less than 0.07) were correlated with nonviral infections.