Objective To invetigate the effectiveness and safety of low molecular weight heparins application in PCI. Methods 224 PCI patiens who were hospitalized from. Apr. 2002 to Jul. 2007 in Huludao Hospital with divided intotwo groups which were using common depo-heparin, and group which were using low-molecular- weight heparins. There were 103 patiens in group which were using common depo-heparin,78 males, average age 65.6 ± 10 and 121 patiens in group which were using low-molecular-weight heparins. 92 males, average age 64 ± 10. Results Clinical data obtained from the two groups has no significant difference. The success rate of operation （98.4% vs 98.0% ）, target vessel revascularization within7 days （ 2 vs patients）, acute thrombosis （0 pstients in both groups）and peripheral vascular complications（ 8 vs 4 patients）of the two groups have no significant difference （P 〉 0.05）. Conclusion Using low molecular weight heparins in PCI is effective and safe.