A web-based application patient follow-up program was developed to create a registry of patients with ankylosing spondylitis (AS) by the Turkiye Romatizma Arastirma Savas Dernegi (TRASD) AS Study Group. This study describes the methodological background and patient characteristics. The patient follow-up program is a web-based questionnaire, which contains sections on socio-demographic data, anamnesis, personal and family history, systemic and musculoskeletal examination, laboratory and imaging data and treatment. Between October 1, 2007 and February 28, 2009, 1,381 patients from 41 centers were included in the registry (1,038 males [75.2%]; mean age 39.5 +/- A 10.7 years). Mean disease duration was 12.1 +/- A 8.5 years, and mean time from initial symptom to diagnosis was 5 +/- A 6.8 years (median 2 years). HLA-B27 positivity was detected in 73.7% of 262 patients tested. Manifestations of extraarticular involvement were anterior uveitis (13.2%), psoriasis and other skin and mucous membrane lesions (6%) and inflammatory bowel disease (3.8%). The prevalence of peripheral arthritis was 11.2%. In 51.7% of patients, the Bath AS Disease Activity Index was a parts per thousand yen4. But since our patients consisted of the ones with more severe disease who referred to the tertiary centers and needed a regular follow-up, they may not represent the general AS population. Disease-modifying anti-rheumatic drugs were being used by 41.9% of patients, with 16.4% using anti-TNF agents. TRASD-IP (Izlem Programi: Follow-up program) is the first AS registry in Turkey. Such databases are very useful and provide a basis for data collection from large numbers of subjects. TRASD-IP gives information on the clinical and demographic profiles of patients, and the efficacy and safety of anti-TNF drugs, examines the impact on quality of life, and provides real-life data that may be used in cost-effectiveness analyses.