An increasing number of drugs have been implicated in the etiology of eosinophilic pneumonia characterized by the development of pulmonary infiltrates, and peripheral blood eosinophilia. Naproxen is a commonly used nonsteroidal anti-inflammatory drug which may be added to the growing list of pharmacologic agents associated with infiltrative pulmonary lesions. A case of eosinophilic pneumonia induced by Naproxen is described. The results of TBLB, a lymphocyte stimulation test, and a challenge test supported this diagnosis.