Conduction disturbances, aortic incompetence, and myocardial fibrosis are known complications in adult patients with ankylosing spondylitis (AS). Its incidence has been reported to be 10% to 30%; however, less attention has been paid to all cardiac arrhythmias. The aim of this study was to evaluate arrhythmias and conduction disturbances in patients with AS using electrocardiograms and Holter monitoring (including heart rate variability analysis) and to estimate its relationships with age, gender, clinical features, and duration of AS. Thirty-one patients with AS (20 to 69 years old, mean 50 +/- 14) and 22 healthy volunteers (26 to 69 years old, mean 49 +/- 13) underwent rheumatologic and cardiologic evaluations. Ventricular extrasystoles were present in 55% of AS patients and in 28% of controls. Supraventricular extrasystoles were present in 94% of AS patients and 100% of controls. The frequency of ventricular extrasystoles was found to be higher in the AS patients than in the control subjects. Significant differences were found in heart rate variability analyses: ultra low-frequency power and root mean square recessive difference (r-MSSD) were lower in the AS group. When the AS group was divided into subgroups (stages 3 and 4), significant differences were found between control subjects and stage 3 patients in PR interval, heart rate (HR), T-wave duration, ultra low frequency, and r-MSSD and between controls and stage 4 patients in HR, T-wave duration, and r-MSSD. QTc and QTd were not significantly different in groups and subgroups and were not correlated with any other clinical or electrocardiographic parameter. Cardiac arrhythmias were more frequent in patients with AS than in the healthy population. Simple electrocardiograms and Holter parameters do not correlate with the incidence of VESs, age, gender, clinical features, and duration of AS.