AIM: To investigate the role that single nucleotide polymorphisms (SNPs) in the promoter of the tumour necrosis factor-alpha (TNF-α) gene play in the risk of inflammatory bowel diseases (IBDs) in a New Zealand population, in the context of international studies.METHODS: DNA samples from 388 patients with Crohn's disease (CD), 405 ulcerative colitis (UC), 27 indeterminate colitis (IC) and 201 randomly selected controls, from Canterbury, New Zealand were screened for 3 common polymorphisms in the TNF-α receptor:-238 G→A, -308 G→A and -857C→T, using a TaqmanRassay. A meta-analysis was performed on the data obtained on these polymorphisms combined with that from other published studies.RESULTS: Individuals carrying the -308 G/A allele had a significantly (OR = 1.91, x2 = 17.36, P < 0.0001)increased risk of pancolitis, and a 1.57-fold increased risk (OR = 1.57, x2 = 4.34, P = 0.037) of requiring a bowel resection in UC. Carrying the -857 C/T variantdecreased the risk of ileocolonic CD (OR = 0.56, x2 =4.32, P = 0.037), and the need for a bowel resection(OR = 0.59, x2 = 4.85, P = 0.028). The risk of UC was reduced in individuals who were smokers at diagnosis,(OR = 0.48, x2 = 4.86, P = 0.028).CONCLUSION: TNF-α is a key cytokine known to play a role in inflammatory response, and the locus for the gene is found in the IBD3 region on chromosome 6p21, known to be associated with an increased risk for IBD. The -308 G/A SNP in the TNF-α promoter is functional, and may account in part for the increased UC risk associated with the IBD3 genomic region. The-857 C/T SNP may decrease IBD risk in certain groups.Pharmaco- or nutrigenomic approaches may be desir-able for individuals with such affected genotypes.