Eosinophilic pneumonias are characterized by a >25% lavage eosinophil count, blood eosinophilia >500 × 109 cells/L, and/or parenchymal eosinophil infiltration on biopsy. Eosinophilic pneumonias are usually separated into transient forms (Loeffler’s syndrome), acute, and chronic. Acute eosinophilic pneumonia frequently mimics ARDS clinically and radiologically and microscopically looks like diffuse alveolar damage with eosinophils. Chronic eosinophilic pneumonia typically shows upper lobe predominant peripheral consolidation on imaging and a variety of microscopic patterns including sheets of eosinophils, a picture of organizing pneumonia with eosinophils, and sometimes eosinophil necrosis and granulomas. All forms of eosinophilic pneumonia respond to high dose steroids, but chronic eosinophilic pneumonia frequently relapses.