[en] Objectives: To compare the efficacy and safety of lumiracoxib with placebo and celecoxib for osteoarthritis (OA) in a 13 week, multicentre, randomised, double blind study. Methods: After a 327 day washout period for non-steroidal anti-inflammatory drugs, 1702 patients with knee OA were randomised to lumiracoxib 200 or 400 mg once daily (od), celecoxib 200 mg od, or placebo (2:2:2:1). A visual analogue scale (VAS) pain intensity greater than or equal to40 mm was required. Primary efficacy variables were OA pain intensity (VAS mm) in the target knee, patient's global assessment of disease activity (VAS mm), and WOMAC pain subscale and total scores at 13 weeks. OA pain intensity, patient's and physician's global assessment of disease activity, and WOMAC (total and all subscale scores) were analysed by visit as secondary variables. Results: Lumiracoxib showed significant improvements in all primary and secondary variables compared with placebo. Lumiracoxib 200 mg od and celecoxib 200 mg od achieved similar improvements in OA pain intensity and functional status. Lumiracoxib 400 mg od demonstrated better efficacy for OA pain intensity and patient's global assessment of disease activity at weeks 2, 4, and 8 and similar efficacy at week 13 compared with celecoxib 200 mg od. The incidence of adverse events (AEs), serious AEs, and discontinuations due to AEs was similar in each group. Conclusion: Lumiracoxib demonstrated significant improvement in OA pain intensity, patient's global assessment of disease activity, and the WOMAC pain subscale and total scores compared with placebo. Lumiracoxib was well tolerated in this study, with overall tolerability similar to that of placebo and celecoxib.