It wasn't until 1990, when the existence of two different cyclooxygenases was hypothesized, based on the evidence that steroids inhibited the increase in COX activity induced by bacterial lipopolysaccharides in macrophages, without any effects on the basal production of prostaglandins or leukotrienes. The first isoform, COX-1 is responsible for the production of "housekeeping" prostaglandins critical to the maintenance of normal renal function, gastric mucosal integrity, platelet aggregation, and the autocrine response to circulating hormones. COX-2 on the other hand is an inducible enzyme, upregulated 20-fold in macrophages, monocytes, synoviocytes, chondrocytes, fibroblasts, osteoblasts and endothelial cells by various inflammatory stimuli and cytochines. Classical findings shown that the therapeutics effects of NSAIDs are largely dependent on COX-2 inhibition, whereas some undesirable side effects are bound to COX-1 blockade, such as gastrointestinal bleeding and renal failure. Therefore, agents that selectively inhibit COX-2 over COX-1 are desirable for the treatment of inflammation. However, since September 2004 reports of increased risk of thrombotic cardiovascular events had accumulated for coxibs, the COX-2 inhibitors. Our goal is to provide an overview of the relevant biology and pharmacology of this enzyme in atherosclerosis.