Tumor necrosis factor α (TNF-α) is a cytokine, secreted from activated macrophage, with a broad range of biological activities including regreesion of tumors, cachexia, septic shock and regulation of immunity. The gene encoding TNF-α is located tandem with the TNFβ gene within the HLA complex, between the HLA-B and C4 genes on chromosome 6p21.3. TNFA gene was typed in 292 normal Korean. For TNFA genotyping, a 107bp seuence containing the TNFα promoter region, which revealed G to A transition at position-308, was amplified by the primers : (TNF A1 5`AGG CAA TAG GTT TTG AGG GCC AT 3` and TNF A2 5`TCC TCC CTG CTC CGA TTCCG 3`) and restriction fragment length polymorphsim (RFLP) was investigated using the restriction endonuclease NcoI. RFLP analysis of TNFA gene showed fragments of 87/20bp and 107bp behaved as TNFA^(*)1 (Tl) allele and TNFA^(*)2 were 0.8356 and 0.1644, respectively. Comparing with allele frequency of European population, it was similar to our result. This results support ethnic background of TNFα and regulation of TNFα expression.