BACKGROUND: The association between premature ovarian failure (POF) and cardiovascular diseases (CVD) was investigated previously, but none of the studies have looked at cardiac autonomic functions in these patients. In this study, we aimed to evaluate cardiac autonomic functions in patients with POF. METHODS: We enrolled 26 female patients (mean age 37.5 +/- 10.1 years) with primary POF and 31 healthy subjects (mean age 37.5 +/- 9.0 years). All participants underwent 24-h Holter recording. Heart rate recovery (HRR) indices were calculated by subtracting 1st-, 2nd- and 3rd-min heart rates from maximal heart rate. Heart rate variability (HRV) and heart rate turbulence (HRT) parameters were analyzed in all patients. RESULTS: Both groups were similar with regard to age, gender, body mass index and left ventricular ejection fraction. Mean HRR1 (p = 0.018), HRR2 (p = 0.021) and HRR3 (p = 0.027) values were significantly higher in the control group. When HRV considered SDNN, SDANN, RMSSD, PNN50 and HF were significantly decreased in patients with POF compared to healthy controls, but LF and LF/HF were significantly higher in POF patients. Both HRT onset and slope were more abnormal in POF patients. Also, there was a significant correlation between HRR, HRV and HRT parameters and FSH, LH and estradiol levels. CONCLUSION: Our study results suggest that cardiac autonomic function is impaired in patients with POF despite the absence of overt cardiac involvement and symptoms. Further studies are needed to elucidate the prognostic significance and clinical implications of impaired autonomic functions in patients with POF.