The aim of the publication was to review available data on epidemiology, pathophysiological and clinical aspects of HFmrEF as a specific HF pattern. Materials and methods: We carried out the analysis of the publications that appeared during last decade, related to the different aspects of HFmrEF. The literature search was conducted by use of Google Web Search and PubMed search engines by the following key words: heart failure, left ventricular ejection fraction, mid-range, as well as their combinations. Conclusions: Patients with specific HF pattern «HFmrEF» demonstrate multidirectional dynamic of systolic heart function with the possibility of transition to the category of reduced or preserved LVEF. Such patients need to be evaluated individually. Their management is based on neurohumoral modulators in order to prevent further LV dysfunction progression and repeated decompensation of HF.