AIDS and HIV infection have stimulated an unprecedented amount of research. In this review we have selected a few publications illustrating key issues. Viral load monitoring is useful because short-term changes in viremia, caused by antiretroviral treatment, predict long-term outcome. Combination therapy with AZT plus either ddl or ddC produces better results than therapy with AZT only, but the differences are slight and appeared only after several years of follow-up. In contrast, the effect of adding 3TC to AZT-containing regimens was statistically significant after only one year, halving mortality and the incidence of new AIDS-defining opportunistic infection. Adding ritonavir had a similar effect after 20 week's follow-up in far-advanced HIV infection. The most potent regimens combine AZT, 3TC, and either ritonavir or indinavir; in the majority of patients thus treated viremia became undetectable (< 500 copies/ml).