Objective: Ankylosing spondylitis (AS) is a chronic systemic disease. The risk of cardiovascular morbidity and mortality is high in patients with AS. Heart rate turbulence (HRT) expresses ventriculophasic sinus arrhythmia and has been considered to reflect cardiac autonomic activity. It has been shown that HRT is an independent and powerful predictor of mortality. The aim of this study was to determine HRT changes in patients with AS in comparison with healthy controls.