In a review of 37,012 autopsies over the last 20 years 202 deceased adults who had had a splenectomy were investigated. The incidence of infections and thromboembolic complications related to death in these patients was compared with that of a matched deceased population (n = 403) who had not undergone splenectomy. Death-related pneumonia was diagnosed frequently in the splenectomy group and to a lesser extent in the control group (57.9 versus 24.1 per cent, P less than 0.001). Lethal sepsis with multiple organ failure occurred in 6.9 per cent of the splenectomy group and in 1.5 per cent of the controls (P less than 0.001). Purulent pyelonephritis was observed in 7.9 per cent of the splenectomy group and was significantly more frequent than in the control group with its rate of 2.2 per cent (P less than 0.001). Finally, pulmonary embolism was the major or a contributory cause of death more often in the splenectomy group than in the control group (35.6 versus 9.7 per cent, P less than 0.001). We conclude that splenectomy generates a considerable life-long risk of severe infection and of thromboembolism.