Abstract: AIM:To evaluate the expression of COX-2 in rabbit atherosclerotic plaque and the relationship between COX-2 and plaque vulnerability. METHODS: The rabbit aortic atherosclerotic model was developed by high cholesterol feeding. Rabbit aorta specimens were measured by HE staining and immunohistochemical staining of COX-2, MMP-2 and I/III collagen. RESULTS: COX-2 was found in atherosclerotic plaques but not in healthy or nonatherosclerotic vascular walls. COX-2, MMP-2 and I/III collagen was induced in atherosclerotic plaque lesions, implicating a relationship between COX-2 and plaque vulnerability. CONCLUSION: Overexpression of COX-2 enhances rabbit atherosclerotic plaque vulnerability.