AIM: To study whether serum tumor necrosis factor alpha gene (TNFalpha) and adhesion molecule levels are indicators of the onset of pregnancy-induced hypertension (PIH), we compared levels of these molecules between normal pregnant women and PIH patients from the first to the third trimester. METHODS: We serially measured serum concentrations of TNFalpha, soluble intercellular adhesion molecule-1 (sICAM-1), soluble E-selectin (sE-selectin), soluble vascular cell adhesion molecule-1 (sVCAM-1) and soluble P-selectin (sP-selectin) using enzyme immunoassay kits in 10 normal pregnant women and 10 pregnant women who developed PIH late in gestation. RESULTS: Serum TNFalpha, sICAM-1 and sE-selectin levels in PIH affected women were significantly higher from the first trimester compared with those in normal pregnancy. sVCAM-1 and sP-selectin levels were not significantly changed. CONCLUSION: Serum TNFalpha, sE-selectin and sICAM-1 levels might be effective indicators of the onset of PIH.