Hospital-acquired pneumonia (HAP) development influences the parameters of mechanical ventilation, intensive care unit (ICU) length of stay, hospital length of stay, need of tracheostomy, bronchoscopy, reconnection to MV and mortality. We respect HAP definition: acute inflammation of the respiratory bronchioles, alveolar structures and pulmonary interstitium. Clinically it is defined as the presence of newly developed or progressive infiltrates on chest radiographs plus at least two other signs of respiratory tract infection: temperature >38 °C, chest pain, purulent sputum, leukocytosis or leukopenia, signs of inflammation on auscultation, cough and/or respiratory insufficiency. HAP is defined as pneumonia that occurs 48 hours or more after admission, which was not incubating at the time of admission. A retrospective, observational study processing data on all consecutive intensive care patients older than 18 years of age between 1 January 2011 and 31 December 2015. The aim was to determine the incidence of potential risk factors and their impact on the development of HAP. The primary outcome was investigation of the relationship between mechanical ventilation parameters and the presence of early- and late-onset HAP. Enrolled in the study were patients staying at the ICU of the Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc and University Hospital Olomouc, between 1 January 2011 and 31 December 2016. The participants were all patients older than 18 years of age consecutively admitted to the ICU.