【Abstract】 Objective To compare the anticoagulation safety and efficacy of the two intravenous methods for low molecular weight heparin administration in continuous renal replacement therapy (CRRT). Methods Seventeen patients with severe acute renal failure with or without multiple organ failure and undergoing CRRT using Fragmin for anticoagulation were enrolled in this study. They were assigned to 2 groups: group A using continuous administration of Dalteparin/Fragmin, and group B using intermittent administration of Dalteparin/Fragmin. Anti-Xa factor activity, coagulation indexes, serum creatinine, and blood urea nitrogen were measured before and after CRRT. Results Anti-Xa factor activity was significantly higher in group A than in group B after continuous veno-venous hemofiltration (CVVH) for 2 hours, but did not differ between the 2 groups at other time points. Activated partial thromboplastin time (APTT) was significantly increased at the end of CVVH in both groups. Conclusion Either continuous or intermittent administration of Dalteparin/Fragmin is safe and effective, but intermittent administration may cause greater variation in anticoagulation status.