Objective To observe the anticoagulant effect of low molecular weight heparin on induced hemodialysis in patients with acute renal failure.Method One hundred and eight patients with acute renal failure treated with induced hemodialysis were randomly divided into low molecular weight heparin(LMWH)group and unfractionated heparin(UFH)group.A bolus disc of UFH was given at first and then maintained by continuous infusion in UFH group,whereas a single bolus dose of LMWH with 2000AFXa IU to 4000AFXa IU in LMWH group.Results Anticoagulant effect between LMWH and UFH did not show significant discrepancy during induced hemodialysis.The bleeding from internal jugular vein catheter increased in the UFH group much more than that in the UFH group was significantly higher than that in the LMWH group.Anti-FXa blood levels were significantly higher in LMWH group than in UFH group.Conclusions LMWH has minor influence on aPTT and TT,while its anticoagulation effect approximates to that of UFH.LMWH represents a realistic alternative agent UFH in acute renal failure induced hemodialysis.