Constriction of 1 renal artery in combination with disruption of the carotid sinus nerves resulted in moderate chronic hypertension in dogs. Hypertension persisted at the same level in some of the animals after removal of the kidney 1 year later, while in others blood pressure decreased somewhat though not to the prehypertensive control level. Narrowing of 1 renal artery without carotid nerve disruption did not lead to significant chronic hypertension. Disruption of the carotid sinus nerves alone, on the other hand, produced mild to moderate hypertension. Constriction of 1 renal artery, if performed several months after carotid nerve disruption, further increased the blood pressure in these animals. Tests of the carotid sinus nerves function by the occlusion reflex of the common carotids indicated a return of function several months after disruption in animals in which the carotid sinus nerves were only crushed. Hypertension persisted in these animals despite the return of the carotid sinus function. Tetraethylammonium choride given intravenously to combined carotid sinus-unilateral renal hypertensive dogs resulted in blood pressure decrease similar to that produced in normal animals. Glomerular filtration rate and renal plasma flow decreased, and filtration fraction increased in 3 dogs following production of the combined type of hypertension.