Abstract： Objective To observe the effects of different doses of human recombinant tissue factor pathway inhibitor-1 (TFPI-1) on no-reflow (NR) phenomenon in rabbit.Methods Fifty-two New Zealand white rabbits were subjected to coronary artery occlusion for 120 min and followed by reperfusion for 60 min,and then were randomly (random number) assigned into four groups:control group,large,moderate and low doses TFPI-1 groups ( 1000 ng/kg,100 ng/kg,10 ng/kg bolus and thenl0 ng/kg,1 ng/kg and 0.1 ng/kg per minute infusion for maintenance,each group n =13).The no-reflow area (NA) and ischemic area (IA) was measured by thioflavin S and Evan's blue.The NR severity was expressed by NA/IA.The difference in NR severity was compared between groups.The thrombi and myocardial injury were observed under light microscope.The infarction and NR severity in different groups were compared by using one-way ANOVA followed by LSD procedure.Results There were no significant differences in IA and body weight among four groups (P＞0.05).NR severity in the large,moderate,low doses TFPI-1 groups and control group were (0.210 ±0.061 ),(0.389 +0.110),(0.478 ±0.077) and (0.536 ±0.061 ),respectively.NR severity in the large dose TFPI-1 group was slightest among the four groups (P ＜0.01 ).NR severity in the moderate dose TFPI-1 group was significantly decreased than that in control group ( P ＜ 0.01 ) and in low dose TFPI-1 group (P ＜0.05 ).There was no significant difference in NR severity between the low dose TFPI-1 group and control group ( P ＞ 0.05 ).There was less thrombus formation and lower grade myocardial injury found in the large dose TFPI-1 group. Conclusion Human rTFPI-1 might lessen NR severity in rabbit in dose-dependent,suggesting the option on human rTFPI-1 for treatment of NR phenomenon.