The non‐Hodgkin's lymphomas (NHL) is a heterogeneous group of tumors derived from B and T lymphocytes and their precursors. In this review we have used a classification scheme of 5 main categories: 1. Follicular lymphomas, 2a. small lymphocytic cell (CLL or immunocytomas), 2b. diffuse small cleaved cell including intermediate lymphocytic and mantle zone NHL, 3. large cell NHL, 4. early B cell (Burkitt's and non‐Burkitt's), 5. precursor cell (lymphoblastic lymphomas). Classification of non‐leukemic post‐thymic T cell NHL is still controversial. Prognostic factors are parameters of tumor burden, proliferative activity, and the condition of the patient. Actual step of tumor progression, the dose intensity of chemotherapy, and the rapidity of tumor regression may also be of importance for outcome. The optimal therapy for follicular NHL remains to be defined. However, the inevitable course of tumor progression and the fact that only achievement of CR offers the chance of a significant fraction of patients being disease‐free leads to the recommendation to treat all younger patients initially. Patients with large cell NHL regardless of stage should be treated with combination chemotherapy. The CR rates have increased with the use of more dose‐intensive regimens suggesting that prognosis for high‐risk subsets might be further improved using high‐dose chemotherapy with autologous bone marrow transplantation as fir