The World Health Organization has included different types of lymphoma under the aggressive category. In the US, diffuse large B-cell lymphoma is the most common aggressive lymphoma and accounts for > 30% of the 55,000 new cases diagnosed annually. Recent advances in the knowledge of the molecular biology have provided an increased understanding of the heterogeneity of non-Hodgkin's lymphoma. New treatments, especially those with the use of monoclonal antibodies, are improving both the survival and the response rate.