Despite wider application of the use of nocturnal intermittent positive pressure ventilation (IPPV) via nasal access for the management of nocturnal hypoventilation, there continues to be a lack of familiarity with the use of IPPV via the mouth for ventilatory support. Unlike nasal IPPV, which is generally practical only for nocturnal use, up to 24-h mouth IPPV was the key method of noninvasive ventilatory support that permitted the avoidance or elimination of tracheostomy for 257 individuals with acute or chronic ventilatory failure. Mouth IPPV was delivered via commercially available mouthpieces for daytime aid and mouthpiece with lip seal or custom orthodontic interfaces for nocturnal support. The use of mouth IPPV alone or in a regimen with other noninvasive ventilatory aids was reviewed for these 257 individuals. Mouth IPPV was used for nocturnal aid by 163 individuals, 61 of whom had little or no measurable vital capacity or significant ventilator-free breathing time, for more than 1,560 patient-years with few complications. It was also the predominant method of daytime ventilatory support for 228 individuals for more than 2,350 patient-years. We conclude that for individuals with adequate bulbar muscle function but chronic respiratory muscle insufficiency, mouth IPPV can be an effective alternative to tracheostomy. It can significantly prolong survival while optimizing convenience, safety, and communication.