We investigated 91 cases of acute cholangitis, including 42 of severe cholangitis and 49 of mild cholangitis. The incidence of endotoxemia was 78.6 percent in 42 and 32.6 percent in the 49 patients. In the 42 with severe cholangitis, remarkable leukocytosis, thrombocytopenia, decrease of serum CH50, C3, plasma fibronectin and phagocytic index were characteristic. Disseminated intravascular coagulation (DIC) was observed in 76.2 percent. Since there was a positive correlation between platelet counts and levels of CH50 and C3, the decrease of platelet count, and the occurrence of DIC in patients with endotoxemia were thought to be closely related to the consumption of complements. There was no difference in mortality rate between nonsurgical treatment (57.8 percent) and the emergency bile drainage treatment (56.5 percent). The results of therapy depended on the degree of complicating DIC. We conclude that acute cholangitis was aggravated by endotoximia and that severe cholangitis was accompanied by DIC induced by a decline in phylaxis.