The pulmonary eosinophilias are characterised by radiographic lung shadows with either a peripheral blood eosinophilia of more than 450/microliter or histologic abnormalities consisting of both interstitial and intraalveolar accumulations of eosinophils and macrophages. We describe the clinical features, radiographic changes, results of bronchoscopy and follow-up studies of three women with chronic eosinophilic pneumonia of unknown aetiology. In all patients the illness resolved rapidly after treatment with corticosteroids, however one patient experienced a second episode after treatment withdrawal. We demonstrate the wide differential diagnosis of the syndrome of pulmonary eosinophilia.