Research is expensive. During the late 1990s the NIH often spent more than $130,000 per year to fund an average research project. Drug manufacturers estimate that they spend an average of $359 million to develop one new drug.

The availability of funding often determines what medical research is conducted. Voluntary health organizations and other groups act as advocates in urging or lobbying the government to spend more on their own particular disease. Governments in developed countries usually spend most heavily on diseases that affect their own citizens, and these diseases are typically different than those commonly found in developing countries. Pharmaceutical companies also emphasize development of the most profitable new drugs, usually for diseases that occur in developed countries.

As a result, little research is done on diseases that kill millions of people in developing nations. In 1998, for instance, the NIH planned to spend only $116 million on malaria and other tropical diseases. While rare in industrialized nations with developed health care programs, malaria kills 1.5 million to 2.7 million people in developing countries each year.