This study will explore the autoantibodies against AT₁-receptor and α₁-adrenergic receptor in patients with hypertension. Forty normotensives and 194 patients with hypertension were recruited for participation in this study. All patients accepted systemic combination drug treatment for antihypertension. According to the treatment results and the definition of refractory hypertension, the patients were divided into two groups: a refractory hypertension group and a non-refractory hypertension group. The epitope of the 2nd extracellular loop of type 1 angiotensin (AT₁) receptor and α₁-adrenergic receptor were synthesized and used as antigens to screen the autoantibodies against AT₁-receptor and α₁-adrenergic receptor by ELISA. The plasma renin activity and concentration of angiotensin II and catecholamine were also examined. The positive rates of the autoantibodies against AT₁-receptor and α₁-adrenergic receptor in patients with hypertension, 26.8% (52/194) and 25.3% (49/194), respectively, were higher than those in normotensives (7.5% and 5%)(p<0.01). Further investigation showed that the frequencies of the autoantibodies against AT₁-receptor and α₁-adrenergic receptor in patients with refractory hypertension, 42.9% (42/98) and 36.7% (36/98), respectively, were higher than those in patients with non-refractory hypertension under systematic treatment (10.4% and 13.5%)(p<0.01). The levels of circulating angiotensin II, catecholamine, proteinuria and serum creatine were also higher in the refractory hypertension group than in the non-refractory hypertension group. The findings showed that the frequencies of autoantibodies against AT₁-receptor and α₁-adrenergic receptor were higher in patients with hypertension, particularly in those with refractory hypertension, and that these autoantibodies might play a role in the pathogenesis of hypertension. (Hypertens Res 2002; 25: 641-646)