Long term data on efficacy and safety of anti-TNF treatment with infliximab in patients with ankylosing spondylitis (AS) beyond 5 years is lacking. These data are important because patients with AS usually are younger and withdrawal of anti-TNF therapy in these patients almost always leads to a disease relapse. Furthermore it is still unclear whether long term anti-TNF treatment in AS patients can inhibit radiographic progression. Patients who participated in the EASIC and the DIKAS trial respectively who were treated with infliximab within these studies for 7 and 10 years respectively are followed up by using clinical outcome parameters every 6 months assessing efficacy and safety of long term treatment. Furthermore radiographs of the spine, if done for clinical indication, are analyzed. It is hypothesized that anti-TNF treatment with infliximab is effective and safe over a time period of 9 and 12 years respectively and that long term anti-TNF therapy may inhibit radiographic progression of the spine.