In 1932, William Loeffler, professor of medicine at the University of Zurich, first recognized an unusual allergic syndrome. Loeffler listed three criteria as characteristic: (1) a mild afebrile illness of short duration with a paucity of general findings, (2) shifting and transient pulmonary roentgenographic changes, and (3) a concomitant but variable increase of blood eosinophils.1Since 1932, however, many cases have been reported that vary considerably from Loeffler's requirements. Some of the patients in the reports were chronically ill with fever, cough, increased sedimentation rate, and pulmonary infiltrations that had persisted for many weeks or months. Even though the allergic process in the lungs is usually benign, this is not always the case, and, since the basic mechanisms involved are probably the same, the concept of Loeffler's syndrome has been enlarged. Since Loeffler's syndrome was recognized, transient eosinophilic infiltrations have been reported in organs other than the lungs. In