1015 patients with ankylosing spondylitis were randomized initially to 6 weeks of either etoricoxib 60mg daily, etoricoxib 90mg daily, or naproxen 1000mg daily. After 6 weeks, patients of the etoricoxib 60mg group were re-randomized to either continue on etoricoxib 60mg daily for 20 weeks or increase to etoricoxib 90mg daily for 20 weeks. Within the first 6 weeks, both etoricoxib 60mg and etoricoxib 90mg demonstrated noninferior efficacy in reducing spinal pain when compared to naproxen 1000mg. At 26 weeks, a similar degree of reduction in spinal pain was observed among all groups. Etoricoxib did not appear to increase the risk of treatment-related adverse events compared to naproxen.