Aim To investigate the effect of monocyte chemoattractant protein (MCP)-1 on the formation of abdominal aorta aneurysm (AAA). Methods AAA model was established by perfusion of pancreas elasticity proteinase in 66 rats, which were divided into control team, Oligodeoxynucleotides (ODNs) team and Lipofectin team. ODNs teams were treated by local application of ODNs, antisense ODNs or scramble ODNs in dosage of 50 μg or 100 μg. Lipofectin and pluronic gel were used. The specimen were havested on 14 d after operation. Results Prominantly infiltration of inflammtory cell was evident in aortic tissue 3 d after operation. MCP-1mRNA was dectected by RT-PCR which increased and reached the peak on 14 d after operation. The expression of MCP-1 and CD68 were measured by immunohistochemistry and Western blotting, and reached the peak on 14 d after surgery. Antisense ODNs could inhibit the expression of MCP-1 mRNA prominantly. Antisense ODNs could prevent AAA formation and had a dosage dependent relationship. Conclusions MCP-1 took part in the formation of AAA. Inhibiting the expression of MCP-1mRNA by antisense technology could reduce the infiltration of macrophage and AAA formation.