Peripheral-acting mu opiate receptor antagonists have been extensively studied for the treatment of opiate-induced constipation in advanced illness for the prophylaxis of postoperative ileus. We document the first intensive care patient to receive methylnaltrexone in an attempt to facilitate enteral nutrition. Gastric residuals markedly decreased and enteral feeding increased after administration of i.v. methylnaltrexone. The patient's ileus resolved coincident with the first injection.