The aim of this 13-week, multicenter, randomized, double-blind, double-dummy, placebo- and positive-internal (celecoxib)-controlled, parallel-group study was to demonstrate the efficacy, safety, and tolerability of lumiracoxib in primary hip osteoarthritis (OA) patients. Eligible patients (n = 1,262; ACR criteria) were randomized (1:1:1) to receive lumiracoxib 100 mg once daily (o.d.) (n = 427), celecoxib 200 mg o.d. (n = 419), or matching placebo o.d. (n = 416) administered orally. The primary objective was to compare lumiracoxib 100 mg o.d. and placebo with respect to three co-primary efficacy variables: the pain subscale of the Western Ontario and McMaster Universities Osteoarthritis Index Likert version 3.1 (WOMAC™ LK 3.1) questionnaire, the function subscale of the WOMAC™ LK 3.1 questionnaire, and patient's global assessment of disease activity (100-mm visual analog scale (VAS)) after 13 weeks of treatment. Of the 1,262 randomized patients, 951 completed the study. All randomized patients were included in the intention-to-treat and safety populations. Lumiracoxib was superior to the placebo (p < 0.001) after 13 weeks for all three co-primary endpoints. By week 13, the patient's global assessment of disease activity (100-mm VAS) improved by 23.3 mm (±SD, 27.83 mm) with lumiracoxib and 13.3 mm (±26.71 mm) with placebo. The WOMAC™ function score decreased by 10.4 (±13.56) with lumiracoxib and 6.8 (±12.55) with placebo. The WOMAC™ pain scores decreased by 3.4 (±4.16) with lumiracoxib and 2.2 (±3.94) with placebo at week 13. Similar results were observed for secondary endpoints: OA pain intensity and WOMAC™ total score. Lumiracoxib was similar to celecoxib for all three co-primary endpoints. All treatments were well tolerated. In conclusion, lumiracoxib is effective in reducing pain and improving function in hip OA patients.