Objectives: The prone position is used for intubated patients with adult respiratory distress syndrome (ARDS) and acute lung injury (ALI). The physiological changes associated with the prone position in nonintubated patients may be even more favorable than in intubated patients. We examined the effect of the prone position on arterial blood gases and patient compliance in four awake, nonintubated patients with hypoxemic respiratory failure. Design: We present four consecutive cases of hypoxemic respiratory failure, in which mechanical ventilation was indicated. An attempt was made to avoid assisted ventilation by placing patients in the prone position, while breathing spontaneously. The effect on the clinical condition and the changes in blood gases were registered. Results: We found good patient tolerance. A rapid increase in PaO2 was found, and intubation was avoided in all patients. No significant complications were registered. Conclusion: The prone position may prove beneficial in some cases of hypoxemic respiratory failure, even in awake patients, by avoiding mechanical ventilation and ventilator-associated complications.