Turning a ventilated patient into the prone position can greatly enhance arterial blood oxygenation independent of ventilator parameters. This article explores the physiology relating to pulmonary ventilation, highlighting an overall improvement in ventilation/perfusion matching as a result of the prone position. A series of small studies seems to suggest that prone positioning can have a dramatic effect on life-threatening hypoxia, including adult respiratory distress syndrome (ARDS) but as yet there have been no large, randomised, multi-centre trials to put beyond doubt the benefits of prone ventilation. Turning the patient prone precipitates many issues in caring for him/her in this position. Many are practical problems and the article goes on to explore a variety of these, including turning and positioning the patient, emergencies and access and the psychological effects of being in the prone position. It is important that nurses understand the physiological basis for any actions, including turning the patient prone, but it is also important that nurses doctors and other professionals appreciate the practical difficulties that this form of management can produce. All team members must work together to ensure a safe, cohesive approach to turning and caring for the ventilated patient in the prone position. © 1999 Australian College of Critical Care Nurses Ltd.