A 37 year-old previously healthy woman developed severe respiratory failure and diffuse pulmonary infiltrates. A diagnosis of Eosinophilic pneumonia was made based on elevated blood counts of eosinophils and high numbers of them in the broncho-alveolar lavage. The patient recovered after steroid therapy and remained well six months later. Most cases of eosinophilic involvement of the lung have a chronic course and only recently has acute eosinophilic pneumonia been recognized. Typical findings on bronchoalveolar lavage and cure with steroid therapy provide the basis for diagnosis.