In 69 children with severe infectious purpura (SIP), anomalies of hemostasis on admission were studied retrospectively. Forty-four children presented with disseminated intravascular coagulation (DIC) and 18 with factor VII deficiency +/- thrombocytopenia +/- antithrombin III deficiency. Seven patients were free of hemostasis anomalies. In 5 children, purpura was necrotic on admission, whereas in 9 additional patients skin necrosis occurred subsequently (5 patients with and 4 without DIC). Among the 18 children (26%) who died, 16 were in the DIC group. Factors II and V, fibrinogen and platelet counts were lower in children who died and were correlated with the prognostic score. In the DIC group, however, factor VII + X level was not correlated with the prognostic score and was equally low in fatal and non-fatal cases. Antithrombin III level was markedly decreased in patients who subsequently developed necrosis. These results indicate that factor VII level decreases early in the course of SIP and that consumption of physiologic coagulation inhibitors probably plays a central part in the development of necrotic purpura.