Continuous treatment with the anti-tumor necrosis factor alpha monoclonal antibody infliximab is efficacious in ankylosing spondylitis (AS), whereas treatment discontinuation results in disease relapse, with variable delay. Objective of this study was to compare efficacy between a continuous treatment with infliximab, and a treatment adapted to symptoms recurrence. Addition of methotrexate (MTX)to infliximab was also tested.