AIM: To observe the effects of continuous epidural block on nitric oxide level in plasma of the pregnancy induced hypertension patients. METHODS: Twenty tow female patients ASA class 1 2, scheduled for lective gynecological surgery served as non pregnancy group. Twenty tow normal late stage gravidas as pregnancy group and twenty tow severe pregnancy induced by pertepsion (PIH) gravidas as PIH group. The intarvenous blood samples were taken immediately before continuous epidural block and 15 min following continuous epidural block before incision. It quantiated the concentration of nitric oxide in plasma by measuring the metalolic production of nitric oxidemitrite and nitrate. RESULTS: Before continuous epidural blcok, nitmic oxide level in the plasma decreased significantly in non pregnancy group and PIH group compared with that in pregnancy group ( P <0 05). Nitric oxide level in plasma increased significantly after continuous epidural block in all three group ( P <0 05 or 0 01), CONCLUSION: Continuous epidural block can improve plasma the nitric oxide level in plasma of the patient with pregnancy induced hypertension indicating to produce therapeutic effect on pregnancy induced hypertension.