The autoantibodies against AT1 receptor (ATR-AA), behaving like an agonist were detected in patients with hypertension. ATR-AA which can blocked by ARB may play a role in the pathogenesis of hypertension. The present study is to explore whether AT1 receptor blocker has superior anti-hypertensive effect in patients with positive ATR-AA hypertension. Patients with 2 grade hypertension were recruited and ATR-AA was assayed by ELISA. A study was carried out and the efficacy of anti-hypertension was compared between candesartan cilexetil and ACE inhibitor imidapril.