Abstract: Objective To explore the significance of the expression endogenous ouabain（EO） in adrenal tissue. MethodsPatients with epinephrectomy in 5 years were chosen（31 cases）, and divided into two groups（high blood pressure in 15 cases and normal blood pressure in 16 cases）. With the streptavidin peroxadase conjugataed（SP） method, the expression of EO in the adrenal tissue was studied. Results The expression of EO was much stronger in high BP group than in normal BP group（ P ＜0 025）. The expression of EO in adrenal tissue was related to concentration of aldosterone in plasma. The level of BP were declined to normal in 12 cases after surgery within 1 w. In other 3 cases, BP was declined but not to normal, however the doses of antihypertensive drugs were decreased and the antihypertensive effect was improved. Conclusion EO may plays role in the pathogenesis of secondary high blood pressure induced by the adrenal hyperplasia diseases.