We report a case of an infant with complex congenital heart disease who was placed on captopril for afterload reduction following cardiac surgery and subsequently developed pulmonary infiltrates with eosinophilia. The patient was readmitted with symptoms of rhinorrhea, poor feeding, and decreased activity level. She was found to have diffuse pulmonary infiltrates on chest radiograph and a marked peripheral eosinophilia without leukocytosis. After discontinuing captopril and starting systemic steroids, her symptomatology rapidly improved, and her eosinophilia and radiographic abnormalities both resolved.