Ten asthmatics with gastroesophageal reflux had scintigraphic evaluation of gastropulmonary aspiration. Five mCi of Tc99m sulfur colloid diluted in 50 ml of isotonic saline were administered by nasogastric tube at bed time and the lungs were imaged the following morning. Imaging in 20 studies yielded no evidence of gastropulmonary aspiration. Scintigraphic evaluation has previously been reported to demonstrate gastropulmonary aspiration in some patients with gastroesophageal reflux and pulmonary disease. This study indicates that the technique may lack adequate sensitivity or that gastropulmonary aspiration in asthmatics with gastroesophageal reflux occurs in only a small subgroup of these patients or at infrequent intervals and is difficult to detect.