Tumor necrosis factor (TNF) may contribute to the susceptibility for autoimmune diseases. We examined TNFbeta gene polymorphisms detected by AspHI and NcoI digestion of genomic DNA in patients with myasthenia gravis (n=105) and healthy controls (n=114). In both groups, the frequencies of TNFbeta alleles were not different. AspHI and NcoI polymorphisms of TNFbeta showed a strong association with HLA-B8 (p < 0.03 resp. p < 0.0001 for AspHI and Ncol) both in patients and controls. Our results imply linkage disequilibrium of TNFbeta alleles with HLA-B8 and in myasthenia gravis we were unable to show a stronger association beyond HLA-B8.