Within the last 10 years we have studied 31 patients, 3 with purpura fulminans, 17 with meningococcal sepsis, and 11 with hemolyticuremic syndrome, who showed evidence of or were suggestive for disseminated intravascular coagulation (DIC). We have administered anticoagulant therapy to all of them. In purpura fulminans the presence of DIC and therapeutic effectiveness of heparin were undoubted. In meningococcal sepsis, in vitro study suggests evidence of DIC to a certain extent, but the benefit of heparin, at first sight, appears to be doubtful. By surveying our overall mortality in meningococcal infections, however, early heparinization of patients with severe fulminant meningococcemia, in particular those with shock, is definitely indicated. In hemolytic-uremic syndrome the in vitro coagulation studies are inconclusive and only indirect evidence of DIC can be demonstrated. The value of heparin, and perhaps the addition of activators of fibrinolysis, in this disorder is disputable