BACKGROUND: Various cardiac pathologies have been linked to ankylosing spondylitis (AS) in various conflicting reports. OBJECTIVES: A pilot exploration is done to search frequencies of structural heart involvement, arrhythmias and heart rate variability (HRV) in AS patients. METHODS: Thirty-five AS patients and 25 healthy people were evaluated with 12-lead electrocardiography, echocardiography and 24-hour Holter monitoring. RESULTS: No patient had significant valvular heart disease except one. Ventricular and supraventricular premature beat counts were significantly higher in AS patients compared to the control group (P = 0.002 and 0.01). Frequency of ventricular premature beats was significantly correlated with isovolumetric relaxation time (IVRT) (r = 0.291 , P = 0.025). Abnormal ECG was defined in 4 AS patients; 2 incomplete right bundle-branch block (RBBB), one left axis deviation and one complete RBBB and left anterior hemiblock. QT and P wave dispersions were not significantly different between AS patients and the control group. Although mitral inflow deceleration time (DT) and IVRT were significantly longer in AS patients (P < 0.001, both), frequency of diastolic dysfunction was not significantly different. Among HRV parameters rMSSD (day time), PNN50 (day time) and SDSD (day and night time) were significantly lower than the control group. There were weak to moderate but significant negative correlations of IVRT and DT with these parameters. CONCLUSIONS: In this small sample there is no significant increase in structural heart disease in patients with AS. Diastolic functions may be affected in the course of disease and this may be associated with increased frequency of premature beats. Day time heart rate variability is decreased and associated with diastolic function parameters of IVRT and DT in AS patients.