Follicular lymphoma is characterized in 85% of patients by the presence of a t(14;18) chromosomal translocation that results in overproduction of BCL2. In this study the distribution of high and low expressing TNF alleles at the TNF (-308) and LTalpha (+252) polymorphic sites in 121 patients with follicular lymphoma and 88 control individuals has been analysed. A reduction in high expressing haplotypes in patients compared to normal controls was found (P = 0.055), with no significant difference observed in response rate or overall survival between patients with high or low expressing haplotypes. These results suggest that the TNF locus, or an adjacent locus within the MHC region, is an important genetic risk factor in this disease.