Comparison of clinical data of 64 patients with centroblastic lymphoma, 55 patients with immunoblastic lymphoma and 31 patients with lymphoblastic lymphoma not only confirmed the original assumption of high-grade malignancy as proposed by the concept of the Kiel classification but also demonstrated distinct clinical differences, particularly between lymphoblastic lymphoma and the two other entities. Rapid lymph node enlargement as well as steep fall of survival curves within the first year after diagnosis were common characteristics. Bimodal age distribution, predominance of males and early generalization of disease were typical features of lymphoblastic lymphoma; elderly patients and patients with the unclassified subtypes of lymphoblastic lymphoma exhibited the worst prognosis. Whereas patients with centroblastic and immunoblastic lymphomas showed similar distribution of age, sex and initial stage of disease, patients with immunoblastic lymphoma presented more frequently with a reduced performance status and showed a poorer response to radio-and chemotherapy resulting in a worse prognosis discernible after the first year of follow-up. Generalization during course of the disease was significantly more frequent in immunoblastic than in centroblastic lymphoma.