The incidence of non-Hodgkin's lymphoma continues to rise. Molecular events in lymphocytes from individuals without lymphoma are found with increasing age and may represent early changes toward malignant transformation. Molecular, immunophenotypic, and histologic data have been used to propose a new classification system and several new entities have been identified. Localized, low-grade non-Hodgkin's lymphoma can be cured by radiotherapy, whereas patients with extensive disease experience a continuous remitting course. The effect of high-dose regimens is yet to be determined. Current therapy cures less than 50% of patients with advanced aggressive lymphoma and randomized multi-institutional trials using several regimens have shown similar outcomes. The addition of high-dose therapy to patients in remission may offer a survival advantage to a high-risk subset. Late complications of myeloablative therapy, including myelodysplasia and leukemia, are being increasingly recognized. A significant advance in the treatment of posttransplantation lymphoproliferative disorders using donor T cells was made and future applications of this approach are anticipated.