Prognosis of chronic heart failure (CCF) is a challenging clinical problem. The role of heart rhythm variability (HRV) in CCF pathogensis is poorly known. This study was aimed at estimating the possibility of using HRV for prognosis of CCF. It included 110 patients (mean age 55.1 +/- 6.4 yr) with CCF symptoms after myocardial infarction. HRV analysis was based on 5 minute records. During the first year; 44 patients developed cardiovascular complications, 20 aggravation of CCF 5 unstable angina, 7 repeated infarction, 9 died. The low-frequency component (LF) of the spectrum was inversely related to age, HR, NT-proBNP, CRP and left ventricular election fraction. Based on the low-frequency component median, the patients were allocated to 2 groups (less than 5.2 ln ms2 and 5.2 ln ms2 or more). Comparison of survival curves by the Kaplan-Meier method showed that at LF < 5.2 ln ms2 the probability of CCF decompensation (p = 0.03), secondary infarction (p = 0.007), lethal outcome (p = 0.03) is significantly higher than at LF of 5.2 ln ms2 or more. It means that LF < 5.2 ln ms is an independent risk factor of CCF decompensation, repeated myocardial infarction, amd lethal outcome.