Scientists and clinicians attending the last "New Directions in Antiviral Therapy" conference in late 1994 could hardly have predicted the revolution in the management of patients with HIV infection that has occurred since. Two new classes of antiretrovirals have been licensed, the second-site RT inhibitors and the protease inhibitors; the long in­ cubation period of active HIV infection, when the infection is clinically latent, is now un­ derstood to be a period of intense viral replication and turnover of CD4 lymphocytes; measurements of HI V RNA concentration in plasma have been shown to be essential tools for monitoring the course of HIV infection, deciding when to treat, and assessing the re­ sults of treatment; and finally, combinations of antiretrovirals, particularly combinations including protease inhibitors, have been shown to have dramatically beneficial effects on patients with HIV infection. These advances, coupled with new drugs for the management of herpesvirus infections, have made dramatic differences in the quality and length of life of HIV-infected patients. Additional advances have been made since 1994 in the prevention or management of influenza virus (zanamavir), respiratory syncytial virus (palvizumab), hepatitis B virus (lamivudine and famciclovir), and enterovirus infections (pleconaril). It is difficult to re­ member that only slightly more than a decade ago there were only a handful of antiviral agents available (none of which were antiretrovirals), and a number of those were either highly toxic, of dubious efficacy, or both.