The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the nation’s medical research agency—making important discoveries that improve health and save lives.

Thanks in large part to NIH-funded medical research, Americans today are living longer and healthier. Life expectancy in the United States has jumped from 47 years in 1900 to 78 years as reported in 2009, and disability in people over age 65 has dropped dramatically in the past 3 decades. In recent years, nationwide rates of new diagnoses and deaths from all cancers combined have fallen significantly.

NIH’s mission is to seek fundamental knowledge about the nature and behavior of living systems and the application of that knowledge to enhance health, lengthen life, and reduce illness and disability.
The goals of the agency are:

• to foster fundamental creative discoveries, innovative research strategies, and their applications as a basis for ultimately protecting and improving health;
• to develop, maintain, and renew scientific human and physical resources that will ensure the Nation's capability to prevent disease;
• to expand the knowledge base in medical and associated sciences in order to enhance the Nation's economic well-being and ensure a continued high return on the public investment in research; and
• to exemplify and promote the highest level of scientific integrity, public accountability, and social responsibility in the conduct of science.

In realizing these goals, the NIH provides leadership and direction to programs designed to improve the health of the Nation by conducting and supporting research:

• in the causes, diagnosis, prevention, and cure of human diseases;
• in the processes of human growth and development;
• in the biological effects of environmental contaminants;
• in the understanding of mental, addictive and physical disorders; and
• in directing programs for the collection, dissemination, and exchange of information in medicine and health, including the development and support of medical libraries and the training of medical librarians and other health information specialists.

With 27 Institutes and Centers, the NIH is the largest source of funding for medical research in the world, conducting its own scientific research through its Intramural Research Program (IRP) and providing major biomedical research funding to non-NIH research facilities through its Extramural Research Program. More than 80% of the NIH's budget goes to more than 300,000 research personnel at over 2,500 universities and research institutions. In addition, about 6,000 scientists work in NIH’s own Intramural Research laboratories, most of which are on the NIH main campus in Bethesda, Maryland. The main campus is also home to the NIH Clinical Center, the largest hospital in the world totally dedicated to clinical research.