Background There are no data available about effectiveness of Nasal High-flow (NHF)in chronic respiratory insufficiency. Methods Eleven COPD patients with stable hypercapnia were adjusted to NHF-system with a flow of 20 l/min. After six weeks patients were switched to non-invasive ventilation (NIV) for another six weeks period. Results NHF led to significant decreases in resting pCO2. Between the devices we found no differences in pCO2 levels. Conclusions NHF may thus be an alternative treatment device in stable hypercapnic COPD patients.