Five polymorphic regions (a to e) have been recognized within the TNF gene region. These polymorphisms appear to be of biological importance as individual alleles have been associated with higher production of TNF and/or an increased risk of rheumatoid arthritis or diabetes mellitus. We report here the detection of four new alleles designated a14 (122 bp), b8 (131 bp), b9 (132 bp), and d0 (122 bp) in patients with rheumatoid arthritis and normal controls from the Pacific Northwest. This increases to 39 the number of alleles now recognized at these loci.