Cyclooxygenase-1 (COX-1) derived eicosanoids promote gastroprotective mucosal defenses and induce platelet aggregation. By sparing COX-1, COX-2 specific inhibitors provide effective anti-inflammatory and analgesic activity while substantially reducing the risk of peptic ulcer disease and GI bleeding compared to dual COX inhibitors (traditional NSAIDs). Clinical studies of the COX-2-selective inhibitors have demonstrated efficacy equivalent to nonselective NSAIDs with significantly lower rates of GI toxicity. The incidence of endoscopic ulcers in some studies with coxibs has approximated placebo. However, as the detection of endoscopic lesions is not always correlated with symptomatic ulcers and ulcer complications, outcome studies of GI safety were performed. The results of large outcome studies have evaluated rofecoxib and celecoxib in over 39,000 patients with osteoarthritis or rheumatoid arthritis. Results of these studies showed that patients taking a supratherapeutic dose of rofecoxib or celecoxib had significantly lower rates of GI-related adverse events than those taking a nonselective NSAID. The GI safety of coxibs for patients using low dose aspirin concomitantly with a coxib appears to be reduced, particularly with regard to ulcer complications. Such data provide support for the COX-2 hypothesis and demonstrate that coxibs provide effective treatment of pain and inflammation with a reduced risk of gastropathy.