Epidemiologic data presented in this review suggest the involvement of hepatitis C virus (HCV) in the patho- genesis of some histotypes of B-cell non-Hodgkin's lymphoma, in particular immunocytoma and lymphomas growing primarily in the liver and major salivary glands. Experimental data further support this hypothesis. Recent findings include demonstration that patients with hematologic malignancies can be treated safely with standard and high-dose chemotherapy even in the presence of HCV infection.