The National Institutes of Health (NIH) is an agency of the United States Department of Health and Human Services and is the primary agency of the United States government responsible for biomedical and health-related research. Its science and engineering counterpart is the National Science Foundation. It comprises 27 separate institutes, centers, and offices which includes the Office of the Director. Francis S. Collins is the current Director.
As of 2003, the NIH was responsible for 28%—about US$26.4 billion—of the total biomedical research funding spent annually in the U.S., with most of the rest coming from industry.
The NIH's research is divided into two parts: the NIH Extramural Research Program is responsible for the funding of biomedical research outside the NIH, while the NIH Intramural Research Program (IRP) is the internal research program of the NIH, known for its synergistic approach to biomedical science. With 1,200 principal investigators and more than 4,000 postdoctoral fellows in basic, translational, and clinical research, the IRP is the largest biomedical research institution on earth.