The regional hemodynamic effects of candesartan cilexetil (TCV-116), a selective angiotensin II AT(1)-receptor antagonist, and enalapril, an angiotensin-converting enzyme inhibitor, were compared in conscious spontaneously hypertensive rats (SHR). A 7-day repeated administration study was carried out. TCV-116 (1 mg/kg, p.o.) and enalapril (10 mg/kg, p.o.) reduced blood pressure to the same extent 5 hr after administration on the Ist and the 7th day. At these points, the cardiac index and organ or tissue blood flow were measured by the non-radioactive colored dye-extraction microsphere technique. Repeated administration of TCV-116, and single and repeated administration of enalapril significantly increased renal blood flow without any changes in the cardiac index. TCV-116 and enalapril also tended to increase splanchnic blood flow following the Ist dose but not the 7th dose. No significant changes in blood flow were observed in the brain, heart, adrenal, skin and skeletal muscle. These results suggest that the antihypertensive effects of TCV-116 and enalapril are attributable to the systemic reduction of vascular resistance caused by the dilatation of blood vessels. These hemodynamic effects of TCV-116, like those of enalapril, may be beneficial in the treatment of hypertension.