 The cardiovascular effects of vitamin D therapy in humans have been documented only in patients with known vitamin D deficiency or hyperparathyroidism a surrogate marker of inadequate vitamin D activity. It is unknown whether the cardiovascular benefits of vitamin D therapy extend beyond these patients to the general hypertensive population. We propose to directly measure the effect of vitamin D therapy on plasma renin activity PRA, plasma renin concentration PRC, renin transcription in mononuclear leukocytes, and blood pressure in hypertensive but otherwise healthy patients in a randomized, controlled, experimental trial. This will be the first study to assess vitamin D receptor VDR biological PRA, PRC, renin mRNA, and polymorphisms and hypertensive activity in patients without vitamin D deficiency. We hypothesize that vitamin D inhibition of renin transcription will produce significant reductions in PRA, PRC, renin transcription, inflammatory cytokines, SBP, and DBP, with potential variation by VDR genotype. Such a result may prove to be significant in the treatment of hypertension, as even modest blood pressure reductions 5 mmHg are associated with a 14 reduction in mortality due to stroke, a 9 reduction in mortality due to CHD, and a 7 overall reduction in all-cause mortality. 