The National Institute of Health is the leading funding source for medical and biological sciences in the United States. The current NIH's yearly budget is a little over $33 billion dollars, and most of it is directed towards funding medical researches across the country.

The National Institutes of Health (NIH) is by far the leading funding source for medical and biological research in the United States. If you search the NIH Grant database its current yearly budget is ~ $33 billion dollars, with 82% directed towards "extramural" funding of over 300,000 medical researchers, at over 2500 research institutions, across the country.