In recent decades the special attention is given to the Heart Rate Variability (HRV) to assess the prognosis of the patients with cardiovascular diseases. There were studied 47 male with arterial hypertension and heart failure, by which the HRV was researched. In the group of patients with type 2 diabetes mellitus (DM), ischemic heart disease (IHD), arterial hypertension (AH) and heart failure (HF), the heart rate variability (HRV) has been considerably lowered in comparison with the group of patients at which the presence of DM was absent. Initial activation of sympathetic nervous system in the group of the patients with DM, IHD, AH and HF, can speak about expected progressing of heart failure even before occurrence of any significant changes of central hemodynamic. It has been established that the higher the functional class of heart failure the sympathetic influences were more brightly shown and as a whole the heart rate variability was worse.