Objective To investigate the appropriate dose of unfraction heparin and low molecular weight heparin (LMWH) in hemodialysis patients. Methods Thirty-eight hemodialysis patients were enrolled and randomly allocated into four groups. The initial bolus dose for the Low-dose (LH, n = 10) and high-dose heparin (HH, n = 10) groups were 35 U/kg and 55 U/kg, respectively. The repeated maintenance dose for both groups were 10 U/kg·h and 16 U/kg·h, respectively. Fragmin were administered as single bolus (60 U/kg or 80 U/kg) at 30 minutes before hemodialysis in Low-dose LMWH (LLMWH, n = 10) and High-dose LMWH (HLMW,n=8) group, respectively. Furthermore, the dialysis circuits in LUFH and LLMWUFH groups were primed with with 4 mg/dl heparinized saline before hemodialysis. Glass bead active clotting time (gbACT), clot rate (CR)and platelet function (PF) were examined using Sonoclot analysator at 0 h ,2 h and the end of hemodialysis at the arterial circuit and 2 h at the venous circuit. Results (1) LH and LUFH: the increase of gbACT and decrease of CR at the arterial circuit and the venous circuit at 2 h of hemodialysis were significant compared with baseline. While they recovered at the end of hemodialysis. No difference between the two groups at different time points was found, either. (2)LLMWH:No change were found in gbACT during hemodialysis. CR at the arterial circuit and the venous circuit were significantly decreased at 2 h and recovered at the end of hemodialysis. (3) LI.MWUFH:gbACT at the arterial circuit was significantly increased only at 2 h of hemodialysis. CR at the arterial circuit and the venous circuit at 2 h of hemodialysis were significantly decreased and recovered when hemodialysis finished. (4) HH and HLMWH: gbACT were significantly increased and CR were rapidly decreased at both the arterial circuit and venous circuit at 2 h of hemodialysis. Conclusion Low-dose heparin was effective and safe as anticoagulant in hemodialysis. Low-dose low-molecular-weight heparin was efficient in anticoagulation to some extent. However, High-dose low-molecular-weight heparin, high-dose heparin and flushing with heparinized saline may increase the risk of hemorrhage.