We determined whether polymorphisms in the promoter region of the tumour necrosis factor alpha (TNF-alpha) gene contributes to differences in susceptibility to develop pre-eclampsia. The study involved 133 pre-eclamptic and 115 healthy pregnant women who were genotyped for the G-308A polymorphism of the TNF-alpha gene. The frequency of the G-308A allele was more common in the pre-eclampsia group than among the controls (P=0.046), giving an odds ratio of 0.57 (95% CI: 0.32-0.99), but there were no differences in the genotype distribution. The data from the G-308A polymorphism was combined with the previously published genotype and allele data from the C-850T polymorphism of the TNF-alpha gene, and used to assess a haplotype estimation analysis. Estimated overall pair of loci haplotype frequencies differed significantly between the groups (P=0.023+/-0.004). In the single haplotype association analysis, the haplotype C-A versus others was over-represented in the pre-eclampsia group (P=0.041+/-0.003), whereas the haplotype T-G versus others was less common in the pre-eclampsia group (P=0.035+/-0.003), compared with the controls. In conclusion, the polymorphisms of the TNF-alpha gene showed a significant haplotype association with susceptibility to pre-eclampsia in the Finnish population.