Two patients with bilateral diaphragmatic paralysis are described. The first case occurred secondary to open chest surgery; the second occurred in a polytraumatized patient. Both were successfully treated with intermittent bi-level positive airway pressure (Bi-PAP). Bilateral diaphragmatic paralysis can be related to a variety of processes, although idiopathic forms also occur. Diagnosis can be difficult and should involve a high level of clinical suspicion. Treatment and prognosis are determined by the underlying disease. Some cases may require the establishment of nighttime support ventilation. Techniques for non-invasive ventilatory assistance such as Bi-PAP can improve symptoms markedly and allow patients to live independently.