Gastroesophageal reflux (GER) is increasingly recognized as contributing to a number of pulmonary disorders. The relationship of GER to pulmonary allograft dysfunction after lung transplantation is unknown. In this report, we describe a lung transplant recipient who developed an acute decline in pulmonary function several months after a retransplantation for chronic rejection. A pulmonary workup at that time, including bronchoscopy with biopsy, revealed bronchial inflammation with no allograft rejection or infection. Because of increasing GI symptoms after retransplantation, the patient also underwent additional testing, which revealed severe acid reflux. The treatment of this patient's acid reflux with Nissen fundoplication surgery resulted in a prompt and sustained improvement in his pulmonary function. We suggest that GER should be considered among the potential causes of allograft dysfunction after lung transplantation.