Objective: To evaluate the effect of Bilevel non-invasive positive airway pressure ventilation (BiPAP) in the treatment of acute respiratory failure. Method: The clinical experimental study. Results: From 06/2008 to 06/2009, 79 patients with acute respiratory failure (included 41 hypercapnic and 38 hypoxemic) were treated by non-invasive ventilation (40 BiPAP and 39 CPAP).