Congestive heart failure (CHF) is a major public health problem that results in tremendous economic burden. Diastolic heart failure (DHF) forms an important subset with increasing incidence and prevalence. There are widely variable estimates of the prevalence, ranging from 13% to 74% of all CHF presentations, and this is predominantly a result of a lack of uniform criteria for establishing a diagnosis. New developments in management of DHF have lagged behind those for systolic heart failure (SHF), for which numerous new therapeutic and device strategies have been instituted. The renin-angiotensin-aldosterone system (RAAS) plays an important role in the pathophysiology of both SHF as well as DHF. The beneficial role of ACE inhibitors as well as aldosterone antagonists in SHF has been well established. Because of its unique role of the RAAS in establishing fibrosis at a molecular level, RAAS blockade provides an opportunity to expand the therapeutic options for DHF. Thus far, in patients with primary DHF only the angiotensin receptor type 1 antagonist candesartan has been reported to decrease morbidity and probably mortality. Large, ongoing randomized trials including TOPCAT (Trial of Aldosterone Antagonist Therapy in Adults with Preserved Ejection Fraction Congestive Heart) and the I-PRESERVE (Irbesartan in Heart Failure with Preserved Systolic Function) are currently underway to establish the role of aldosterone antagonists in patients with DHF.