• Gastroesophageal reflux (GER) was initially diagnosed in two black infants, aged 5 and 9 months, as a cause of their chronic lung disease and failure to thrive. Both infants were treated with bethanechol chloride as part of the management of their GER, but respiratory failure developed in both patients and they required ventilatory support. Both infants had severe air trapping, CO2 retention, difficulty in being weaned from mechanical ventilation, and Staphylococcus aureus cultured from their respiratory tract secretions. These factors led to the suspicion of cystic fibrosis (CF), and this diagnosis was subsequently confirmed by sweat test. The condition of both infants improved substantially on withdrawal of bethanechol therapy and the institution of a regimen of CF care. The early diagnosis of GER in these infants may have led to a delay in diagnosis and treatment of CF.