Objective: To describe the effects of enteral naloxone used to treat opioid-induced constipation in pediatric intensive care patients. Design: Retrospective chart review. Setting: Pediatric intensive care unit. Patients: Twenty-three patients who received opioid therapy and enteral naloxone in our institution from January 2003 to February 2004 were compared with a randomly sampled control group matched for age, weight, sex, and length of stay who received opioids but had not received enteral naloxone. Interventions: None. Measurements: Daily stool output, daily opiate usage, nutrition, adjuvant laxative use, and side effects were assessed. Results: Patients stayed an average of 5 days (range, 0-13 days) in the pediatric intensive care unit before enteral administration of naloxone was instituted and received it for an average of 9 consecutive days (range, 3-30 days). Mean stool output for study patients before administration of enteral naloxone was 0.14 ± 0.38 stools per day, whereas after its initiation it was 1.60 ± 1.14 stools per day (p < .001). However, two patients developed significant opiate withdrawal symptoms after receiving enteral naloxone. The average stool output for control patients was 0.53 ± 1.21 stools per day. Conclusions: Enteral naloxone may be effective in increasing stool output in opioid-induced constipation but carries the risk of introducing withdrawal symptoms. Further studies are needed to evaluate this agent for opioid-induced constipation in the intensive care unit. Copyright © 2006 by the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies.