We describe a case of severe gastric insufflation in a patient with amyotrophic lateral sclerosis who was receiving bilevel nasal positive airway pressure (BNPAP) ventilation (BiPAP; Respironics; Murrysville, PA). The injection of inspiratory flow into the esophagus, aerophagia, and air trapping below the gastroesophageal junction after a meal are probably the major causes. We suggest that BNPAP ventilation can be a cause of serious gastric insufflation in a patient who lies supine, especially after a meal, and attention should be paid to avoiding this complication by having the patient sit up for about half an hour after a meal.