The term “eosinophilic lung disease” encompasses a heterogeneous group of disorders characterized by eosinophilic infiltration in the lung, radiographic abnormalities, impaired lung function, and commonly peripheral blood eosinophilia. These disorders can occur secondary to a variety of causes including infections (especially parasitic and fungal), drug/medication reaction, primary connective tissue diseases, allergic bronchopulmonary aspergillosis, Churg-Strauss syndrome, as a paraneoplastic syndrome to lymphoma or metastatic disease, or due to a primary marrow process. Those patients without an identifiable cause are referred to as having eosinophilic pneumonia. Because the signs and symptoms of these conditions can overlap, a careful assessment including a detailed history (with medication and travel history) and physical examination is necessary. Most patients with chronic eosinophilic pneumonia have peripheral blood eosinophilia. Elevated peripheral blood eosinophil count is itself a relatively common finding in general medicine practice and, similar to eosinophilic lung disease, is most often secondary in nature.