A multicenter cooperative study was carried out involving 47 nationwide institutes in Japan to assess the efficacy and safety of low molecular weight heparin (Fragmin) on DIC. Fifty-six DIC cases were challenged by Fragmin injection principally for 5 days with the doses of 75 U/kg/day in the I group (n = 27) and 150 U/kg/day in the II group (n = 29). Scoring points were defined based on the severity of bleeding symptoms, organ failures and abnormal coagulation-fibrinolytic examinations, and therapeutic effect of Fragmin was evaluated objectively according to the improvement degrees of these scores. Six cases (10.7%) died of the underlying diseases or complications other than DIC and hemorrhagic side effects occurred in 3.7 and 10.3% cases of the I and II groups, respectively. However, in bleeding symptoms, 45.5 and 31.6% cases of the I and II groups improved excellently or moderately. In organ failures and coagulation-fibrinolytic examinations, remarkable improvement was observed in 31.6 and 66.7% cases of the I group, while they remained 14.3 and 51.7% in the II group, respectively. The overall utility of Fragmin was 66.7% in the I group and 58.6% in the II group. These results demonstrate that Fragmin is effective on DIC with a dose of 75 U/kg/day.