Barium esophagrams of 160 infants who were being examined for apneic episodes were obtained at a referral center for the investigation of sudden infant death syndrome (SIDS). The studies were standardized as closely as possible to evaluate swallowing, esophageal function and anatomy, and the gastroduodenal regions. The level and frequency of gastroesophageal reflux were carefully assessed. The most common abnormality identified was gastroesophageal reflux (54%). Other abnormalities included nasopharyngeal reflux (27%), aberrant right subclavian artery (3%), and aspiration into the airway (3%). Swallowing dysfunction, esophageal dysmotility, antral dysmotility, chalasia, and tracheoesophageal fistula were each found in less than 1% of the infants.