OBJECTIVES: This study aimed to examine the efficacies and gastrointestinal(GI) safeties of celecoxib and non-steroidal anti-inflammatory drugs(NSAIDs) in the treatment of osteoarthritis and rheumatoid arthritis. METHODS: A systematic review of randomised controlled trials (RCTs) which compare celecoxib with NSAIDs and report their efficacies or gastrointestinal safeties was performed by two independent reviewers. Searches were made by using electronic databases, such as MEDLINE, EMBASE and Cochrane Library, from 1975 up to 2008, as well as by hand searching for Korean articles. After reviewing all eligible RCTs, including local trials, reported results were combined using either a fixed effect or a random effect model according to their statistical evidences of heterogeneity. Outcome measures for efficacy were WOMAC index, Patients and physician’s global assessment and VAS pain score. For gastrointestinal safety, ‘ulcer and POB(perforation, obstruction and bleeding)’ and mild GI symptom were used. Effect measures pooled were odds ratios or mean differences from baseline to post-treatment, according to our pre-planned protocol. RESULTS: Included in the review were 10 RCTs for efficacy and 14 RCTs for GI safety. Celecoxib showed the same efficacy as other NSAIDs for all efficacy measures. However, patients taking celecoxib showed 72% lower incidence of ulcers and POB (pooled OR=0.28, 95% CI=0.17 to 0.45) and 37% lower incidence of GI mild symptoms (OR=0.63, 95% CI=0.55 to 0.72) than those taking NSAIDs. For the incidence of ulcer and POB, subgroup analysis for patients with negative H. pylori patients showed lower incidence (OR=0.07, 95% CI=0.03 to 0.18) than the overall result, while for those with positive H. pylori it remains same (OR=0.27. 95% CI=0.14 to 0.52). The sensitivity analysis of excluding Korean RCT showed an increased OR for mild GI symptoms (OR=0.73, 95% CI=0.65 to 0.81). CONCLUSIONS: Celecoxib is as effective as other NSAIDs for controlling pain symptoms. However, celecoxib significantly improves GI safety, comparing to other NSAIDs, in the treatment of rheumatoid arthritis and osteoarthritis patients.