To study whether the development of hypertensive disorder complicating pregnancy is associated with -308G-->A, -850C-->T mutation at promoter of TNF-alpha gene, the -308G-->A, -850C-->T polymorphism was examined in patients and healthy pregnant women by PCR-RFLP technique. The frequencies of genotype and allele were compared between the two groups. The results showed that with -308G-->A polymorphism distribution, the allele frequency of TNF2 and the frequency of the genotype TNF2/1 in the patient group was significantly higher in the patient group than in control group (P<0.05). A significant difference in genotype distribution of -850C-->T polymorphism was observed between the two groups. The allele frequencies of T in patient group was higher in the control group as compared with the patient group. The frequencies of CT and TT genotypes were lower in the patient group. It is concluded that the TNF2 allele of -308 is associated with the occurrence of hypertensive disorder complicating pregnancy, while T allele of -850 may be the protective factor against the development of the disease. TNF2/1 CC may be susceptibility genotype of hypertensive disorder complicating pregnancy.