 We, the researchers at Emory University, will recruit patients with hypertension and randomize them to various doses of BH4 to find out what the lowest dose is that produces a significant response This dose will then be used in patients with hypertension who will be randomized to BH4 or a placebo. Patients will be followed for blood pressure response and for markers of endothelial function using ultrasound and for markers of inflammation using blood samples. 