Background. Obesity rates are increasing in the general population and are also prevalent in intensive care units (ICUs). Patients are sometimes admitted to ICUs for hypercapnic respiratory failure or cor pulmonale, but more often, they are admitted for pneumonia, excessive daytime sleepiness, heart failure, chronic obstructive pulmonary disease (COPD), asthma attacks or pulmonary embolism, and hypercapnic respiratory failure is coincidentally noticed during this period. The optimal noninvasive mechanical ventilation strategy is often not used during ICU treatment. The aim of this study was to assess the differences between non-invasive ventilation (NIV) strategies and the outcomes of obese and non-obese patients with acute hypercapnic respiratory failure.