The eosinophilic lung diseases are a heterogeneous group of disorders characterized by pulmonary impairment in the setting of elevated numbers of eosinophils in the peripheral blood and/or lung tissue. Although the pulmonary abnormalities associated with eosinophilic lung diseases classically manifest as abnormal chest radiographic findings, a wide variety of clinically significant symptoms, physiologic changes, and/or gas exchange abnormalities may be seen. The degree to which these individual disorders are related remains unclear. Nevertheless, the simultaneous presence of blood or tissue eosinophilia and pulmonary impairment is useful as a clinical paradigm, because it generates a limited and interesting list of potential diagnoses. Since both prognosis and therapy differ among the disorders, it remains important for the clinician to make a specific diagnosis, which requires an intimate knowledge of the distinguishing features of each condition. This review focuses on the typical presenting clinical manifestations, general diagnostic approach to, and treatment modalities for each of the eosinophilic lung diseases.