Acute respiratory failure due to chronic obstructive pulmonary disease presents an increasing problem for both health and economics in the modern world. The goal of this study was to compare invasive and noninvasive mechani-cal ventilation for patients with COPD. A prospective, randomized trial was performed in a multidisciplinary intensive care unit. Of 614 patients requiring mechanical ventilation (MV) longer than 24h, after excluding those who didn't meet the inclusion criteria, 72 patients with COPD remained the research sample. The MV procedure was per-formed using standard methods, applying two MV methods: invasive MV and noninvasive MV. Patients were ran-domized into two groups for MV application using closed, non transparent envelopes. Comparison was made based on patient characteristics, objective parameters 1h, 4h, 24h, and 48h after admission and finally treatment outcome. In patients with COPD NIMV had statistically better outcome compared to IMV with MV duration NIMV:IMV 102:187h, p < 0.001, time spent in ICU 127:233h, p < 0.001. Need for intubation/reintubation 16 (42.1%):34 (100%)/4 (11.8%), p < 0.001, hospital pneumonia 2 (5.3%):18 (52.9%), p =0.001. Applying strict application protocols, and based on com-parison of objective parameters of pulmonary mechanics, biochemistry and finally treatment outcome, high advantage of NIMV method was confirmed.