The National Heart, Lung, and Blood Institute (NHLBI) is the third largest Institute of the National Institutes of Health, located in Bethesda, Maryland, United States. It is tasked with allocating about $3.0 billion in tax revenue per year (fiscal year 2015 estimate) to advancing the understanding of the following issues: development and progression of disease, diagnosis of disease, treatment of disease, disease prevention, reduction of health care disparities within the American population, and advancing the effectiveness of the U.S. medical system. NHLBI's Director is Gary H. Gibbons, M.D.