Young normotensive, male and female rats which develop hypertension spontaneously as they mature were gonadectomized when they were 30 days old. With time, intact controls and sham-operated controls showed a progressive increase in their blood pressure, attaining systolic pressure levels of 180 to 200 mm Hg when they were 120 days old. During this same period, the gonadectomized animals manifested a slight increase in blood pressure without becoming hypertensive. In keeping with their normotensive levels, the gonadectomized rats did not develop any cardiac or renal enlargement. Orchiectomy was associated with retardation of growth, an increase in the ratio of adrenal weight/body weight, concomitant with increased circulating levels of DOC in males vs. reduced DOC levels in females. There was no change in aldosterone levels in either sex. Cmpd. B levels were increased in the gonadectomized males and were slightly reduced in the gonadectomized females. The changes in Cmpd. B, DOC, and aldosterone in these gonadectomized animals cannot account for the inhibition of the spontaneously developing hypertension.