Thirty-three trauma patients presenting with hypoxemia and normo- or hypocarbia were treated with continuous positive airway pressure (CPAP) via a snug-fitting face mask. All patients had demonstrated continued hypoxemia despite supplemental oxygen administration before institution of CPAP therapy as the primary mode of ventilatory support. Therapeutic end-point of PaO2/FIO2 greater than 300 was achieved in 32 of 33 patients. Duration of CPAP treatment was 28 +/- 19 hours. Two patients (6%) required intubation, but neither for elevation in PaCO2. CPAP mask appears an effective means of support for mild to moderate post-traumatic respiratory insufficiency.