Induction of hypertension by implantation or injection of deoxycorticosterone acetate (DOCA) requires a dose well above the physiological range. The objective of this study was to produce hypertension in rats by chronic infusion of d-aldosterone, a more potent mineralocorticoid. Aldosterone infused at a dose of 1 μg/hr for 4 weeks gave a maximal rise in systolic blood pressure (132 ± 3 vs 203 ± 7 mm Hg). A significant rise in blood pressure was achieved at 0.1 μg/ht (170 ± 6 mm Hg) which was associated with a 2.3- fold rise in plasma aldosterone levels (7.6 ± 0.4 vs 17.7 ± 2.2 ng/dl). A series of isotope flux studies on the aorta and femoral artery from hypertensive animals demonstrated increases in “K and MC1 turnover. In both vessels the largest changes in ion turnover were observed in vessels from animals infused with aldosterone at 0.25 fig/hr. Increases in ”K and 9<G turnover were detected as early as 1 week after the start of aldosterone infusion, well before a significant rise in blood pressure had occurred. (Hypertension 4: 374–381, 1982)