Aim. To assess role of 24 hour heart rate variability (HRV) for prognosis of patients with chronic heart failure (CHF) and systolic dysfunction in the era of wide use of b-adrenoblockers. Material. Patients (n=135) with symptomatic CHF and ischemic (68%) or nonischemic cardiomyopathy (32%) with systolic left ventricular (LV) dysfunction and sinus rhythm (age 52+/-11.9 years; 42, 40 and 18% with NYHA class II, III and IV, respectively; mean LV ejection fraction 30.1+/-6.7%) At study entry 89 and 78% of patients received angiotensin converting enzyme inhibitors and b-adrenoblockers, respectively. Methods. Holter ECG monitoring with HRV temporal and spectral analysis. Results. During average follow-up of 2.4 years 60 patients (44.4%) died of cardiac causes (92.3% of all deaths). Other deaths were due to surgical pathology (n=1) and stroke (n=2). All standard HRV values with the exception of high frequency power were lowered, this lowering correlated with functional severity of heart failure. According to multifactorial analysis the following characteristics were independent predictors of all cause death: NYHA class III-IV (RR=1.9, 95% confidence interval 1.1-9.6, p=0.002), and SDNN value 90 ms (RR=1.5, 95% confidence interval 1.2-2.5, p=0.001). Conclusion. In CHF parameters of HRV are lowered compared to normal values and correlate with functional heart failure severity. NYHA class III-IV and lowered HRV (SDNN 90 ms) allow to identify patients with high risk of death.