Context.—Diagnosis and classification of lymphomas are based on the morphologic, immunologic, and genetic features that the lesional cells share with their normal B and T lymphocyte counterparts. Primary pulmonary lymphomas account for 0.3% of primary lung neoplasms and less than 0.5% of all lymphomas.Objective.—To describe and summarize the clinical and histopathologic features of the primary pulmonary lymphoma and secondary involvement of the lung by lymphoma.Data Sources.—Peer-reviewed published literature and personal experience.Conclusions.—Diagnosis of clonal lymphoid proliferations in the lung has evolved owing to the greater utility of molecular and flow cytometric analysis of tissue. Further studies are needed to best define the clinical and prognostic features, as well as search for targeted therapy for these patients with rare neoplasms.