Objective. Autonomic neuropathy and impairment of left ventricular functions (LVF) have been frequently encountered in chronic renal failure (CRF). The aim of the present study was to evaluate the relationship of cardiac autonomic modulation impairments, as assessed by means of heart rate variability (HRV), with clinical characteristics, and left ventricular function in the patients with CRF undergoing hemodialysis (HD). Methods. Twenty control subjects (Group I) and 22 comparable by age and gender patients with CRF undergoing hemodialysis (Group II) were enrolled in the study. After routine clinical and biochemical evaluations, electrocardiography, and 2 Dimensional, M Mode echocardiography were performed in all participants. Frequency domain HRV analysis was studied by using Kardiosis System. The powers (P-1 and P-2) and the central frequencies (F-1 and F-2) of low and of high frequency spectral bands were recorded. Results. End systolic (ESV) and end diastolic volumes (EDV) were significantly higher in Group II (59.3 +/- 21.1 mL vs. 34.0 +/- 14.3 mL and 131.5 +/- 37.3 mL vs. 96.9 +/- 18.9 mL, p < 0.01, p < 0.05, respectively) when compared to those of Group I. Ejection fraction (EF) and fractional shortening (FS) were significantly lower in Group II than in control subjects (52.3 +/- 2.4% vs. 63.7 +/- 10.1% and 0.29 +/- 0.01 vs. 0.34 +/- 0.07, p < 0.001, p < 0.05, respectively). P1 and P2 were decreased in Group II than in Group I (136.2 +/- 173.9 m s(2) vs. 911.0 +/- 685.5 and 96.5 +/- 149.6 vs. 499.7 +/- 679.5, p < 0.001, p < 0.01, respectively). Significant correlations were found between high frequency spectral power and dialysis duration (DD), ESV, EDV, EF, FS (r = 0.52 p < 0.01, r = 0.68 p < 0.001, r = 0.65 p < 0.002, r = 0.66 p < 0.02, and r = 0.69 p < 0.01). Conclusion. As a result, the dependence of cardiac autonomic neuropathy on the disease duration and degree of left ventricular function impairment was shown in the patients undergoing chronic hemodialysis.