Hairy cell leukaemia (HCL) is a rare chronic B lymphoproliferative disorder which can lead to severe pancytopenia and several immunologic abnormalities. The pathogenetic role of tumour necrosis factor (TNF)-alpha in HCL prompted us to study the potential contribution of functionally important genetic polymorphisms of the TNF gene cluster in a large group of patients with HCL. The TNF-alpha (-308 bp) promoter/enhancer point mutation and two polymorphisms located within the first intron of the lymphotoxin (LT)-alpha gene showed neither significant allelic deviation for the patient group nor, after analysis of clinical characteristics such as blood counts, stable or progressive disease or response to therapy.