In recent years there have been major advances in understanding the pathogenesis of human immunodeficiency virus 1 (HIV-1), as well as a dramatic increase in the number of antivirals available to treat acquired immune deficiency syndrome. The discovery of HIV-1 co-receptors has shed light on the mechanism of virus tropism. Achievement of undetectable virus levels in the plasma of AIDS patients on triple drug therapy has renewed optimism regarding the potential for long-term control of infection.