As can be seen from the preceding brief discussion, the prospects for new antiviral agents for the treatment of viral diseases ranging in severity from the common cold to AIDS appear promising. The latest advances in technologies such as crystallography, genetic engineering, and monoclonal antibodies are all being applied to the discovery of new ways to inhibit virus-specific processes. In addition, the development of diagnostic tests for viral diseases has proceeded at a rapid pace that should facilitate the proper use of the antivirals when they become available. The one lesson that has been learned in the antiviral field over the past decade is that virus-specific inhibitors do exist, and if an essential virus-specific process or protein can be identified, it is likely that a molecule can be found to inhibit or inactivate it.