TGF-beta mediates disease pathogenesis in Marfan syndrome and contributes to aortic stiffness. The angiotensin receptor blocker, losartan, inhibits TGF-beta activity and reverses aortic wall pathology in a Marfan mouse model. Losartan also decreases aortic stiffness and improves diastolic function in hypertension, renal disease and hypertrophic cardiomyopathy.