Based on data obtained from 260 patients ventilated through a mouth-piece, several notions concerning equipment and supervision requirements have become clear.--In our opinion, the indications should not be reserved for extremely severe patients; in their case cardiac complications are constant in spite of usual treatment. These patients, most often respiratory encephalopathic, are not very receptive to the "directions for use" of home assisted ventilation.--On the contrary, chronic hypoxia-hypercapnia, whatever its origin, accompanied by slight or transitory cardiac signs, has much more chance of being treated successfully.--The adaptation of the patient to the respirator before his release from the hospital must be worked out until a clinical and biological improvement can be obtained, at the risk of probable failure.--Supervision at home should disclose any alteration in the patient's clinical condition. It can only be carried out by the conjoined visits of the practicing doctor, nurse, technician, etc. The contacts between the practicing doctor and the hospital physician should be frequent. The ideal solution is systematic visits to the hospital.