Pneumonia is a most common human disease and a leading cause of death from infectious pathology. The mortality rate amounts to 5.20% despite the improvement of the existing methods of treatment. Over 37,000 patients die from pneumonia each year in Russia. Severe pneumonia is an especially serious challenge. The aim of this work was to study the incidence of severe clinical variants of pneumonia (SP), elucidation of its main phenotypes and predictors of adverse outcome. It included retrospective analysis of 101 cases of SP diagnosed based on generally accepted criteria. The clinical symptoms of SP, its incidence, relationship between SP and sepsis are considered along with predictors of adverse outcome. The main phenotypes of SP are distinguished according the leading resuscitation syndrome (SP with sepsis without multiple organ failure (6.9%) including SP with clinical manifestations of acute respiratory failure/acute respiratory distress syndrome (4.0%), SP with severe sepsis (93.1%) including SP with septic shock (26.7%). Bacteremia was documented in 10.1% of the patients. Estimation of the cases with favourable outcome of SP using APACHE II, MODS-2 and SOFGA integral scales gave values of 12.4, 4.7 and 5.4 respectively. They were increased by a factor of 1.7, (APACHE II) and 1.9 (MODS-2 and SOFA) in the patients who died from pneumonia. These values can be regarded as predictors of adverse outcome of SP.