In 2004, new cases of non-Hodgkin's lymphoma in the United States were estimated at 54,370, representing 4% of all cancers and resulting 4% of all cancer deaths, and new cases of Hodgkin's lymphoma were estimated at 7,880. The appropriate staging and management of lymphomas greatly depend on an accurate pathological diagnosis and classification. The recently established Revised European-American Classification of Lymphoid Neoplasms (REAL) and the subsequently adopted and updated World Health Organization (WHO) classification include modern cytogenetic, molecular, and immunologic techniques and knowledge and reach an international consensus on the classification of lymphomas. This classification scheme represents an advance in our understanding of lymphomas and serves as an operative guideline for studying and diagnosing lymphomas. Imaging techniques always have served as staging and monitoring tools for the clinical management of lymphomas. The understanding and adoption of the current classification system is important in refining the role of imaging modalities in the management of specific lymphoma. To help one understand the current classification, this current review gives a brief history of lymphoma classifications and summaries the recent classification schemes, including new entities, clinical staging methods, and clinical prognostic criteria.