• We have examined the use of radionuclide milk scanning to detect aspira[ill]tion and have compared the clinical features of patients with demonstrated aspiration with those of patients in whom aspiration was not demonstrated. One hundred twenty children underwent radionuclide milk scanning for three different clinical Indications, namely, respiratory tract symptoms (n=56), gastroesophageal (GO) reflux (n=20), and near-miss sudden Infant death syndrome (SIDS) (n=44). Ninety-eight (82%) of the 120 patients had a GO reflux demonstrated on the radionuclide milk scan. The Incidence of aspiration was high in the respiratory (23%) and near-miss SIDS groups (20%) but low in the GO reflux group (5%). Only four of the 19 patients with an aspiration-positive scan had an aspiration-positive barium swallow film. The clinical symptoms and signs of those patients with aspirationPositive results were not significantly different from those of patients in whom aspiration was not demonstrated. We conclude that radionuclide milk scanning is more sensitive than barium swal[ill]ow roentgenography in detecting asplration; however, the clinical significance of such aspiration is undetermined. In view of the high Incidence of GO reflux demonstrated in the absence of aspiration by the use of radionuclide milk scanning, the sole finding of GO reflux in a child with respiratory tract symptoms should not be taken as presumptive evidence that aspiration is contributing to those symptoms.