Aim: The aim of this study was to estimate the prevalence of ankylosing spondylitis (AS) in the Eastern Black Sea region of Turkey. Method: The study was conducted by The Department of Physical Medicine and Rehabilitation, Karadeniz Technical University Medical Faculty, in the urban area in the Eastern Black Sea region of Turkey, which has a population of 459,021 (according to the 2000 national census). A total of 4031 subjects over 20 years-old were enrolled, using the sampling method; 2025 (50.7 %) men and 2006 (49.3 %) women were included in the study. A survey consistent with Modified New York Criteria 1987 was used to diagnose AS in patients. The survey was applied and evaluated by two physical medicine residents and 8 trained medical students. Suspected cases were invited to our clinic. Result: Forty one out of fifty patients suspected with AS attended our out- patient clinic. Following physical examination, laboratory tests and radiological investigations of those individuals with suspected AS, 10 ones were diagnosed as AS. 9 of 10 patients were male and 1 patient was female. Patients’ mean age was 40.5 ± 8.4 years. The prevalence was estimated to be 0.25 % (95% CI: 0.09 %-0.40 %). It was 0.44 % in men (95 % CI: 0.15-0.73) and 0.05 % in women (95 % CI: 0.0-0.15) according to gender distribution. Conclusion: The study had value of regional features for evaluating for epidemiology of AS in Turkey. The prevalence of AS was found to be as 0.25 %. A male predominance was noted among AS patients in the study.