Home mechanical ventilation (HMV) is the treatment of choice for patients with chronic hypercapnic respiratory failure. Since the middle of the 1980's, the number of cases under HMV has markedly increased. Presently, at our centre (n=176 patients), obesity-hypoventilation syndrome (36%), and COPD (21%) are the most frequent indications for HMV. Classical indications such as sequellae of tuberculosis, or poliomyelitis, kyphoscoliosis, or neuro-muscular diseases, represent 25% only of our HMV population. Bi-level pressure support ventilators have replaced the volumetric ventilators used in the 80's in most situations. A specialized team of nurses monitors closely at home clinical evolution, and compliance, gathering an important amount of clinical data, and allowing the early detection of clinical deterioration.