The role of circulating bradykinin in blood pressure regulation was investigated in conscious normotensive rats using a competitive antagonist of bradykinin. The acute blood pressure effect of this antagonist was also evaluated after inhibition of angiotensin converting enzyme with captopril and during simultaneous infusion of exogenous angiotensin II. No evidence was found for a role of circulating bradykinin in rats studied under normal conditions. Endogenous bradykinin seemed however involved in blood pressure control during angiotensin II infusion. Acute angiotensin converting enzyme inhibition had no influence on the blood pressure response to the bradykinin antagonist.