During the next four years in this nation, the epidemic of human immunodeficiency virus (HIV) infection and its most severe manifestation, acquired immune deficiency syndrome (AIDS), will claim over 200,000 lives. The U.S. Public Health Service estimates that 1 million to 1.5 million people are currently infected with the virus. In the absence of effective therapy, the vast majority of those infected will develop AIDS and die. Although AIDS now kills fewer people than heart disease or cancer, its rank as a cause of mortality is quickly rising, and the primary sufferers of AIDS come from what is ordinarily a healthy and productive population group: young adults.