The most dreaded complication of tube feedings is tracheobronchial aspiration of gastric contents. Strong evidence indicates that most critically ill tube fed patients receiving mechanical ventilation aspirate gastric contents at least once during their early days of tube feeding. Those who aspirate frequently are about 4 times more likely to have pneumonia develop than are those who aspirate infrequently. Although a patient's illness might not be modifiable, some risk factors for aspiration can be controlled; among these are malpositioned feeding tubes, improper feeding site, large gastric volume, and supine position. A review of current research-based information to support modification of these risk factors is provided. (American Journal of Critical Care. 2006;15:360-369)