We report here the use of a simple, rapid, reproducible, and quantitative assay to detect the putative activity of anti-HIV agents. It can be employed with different T cell cultures, such as peripheral blood lymphocytes or CEM-C113 cells, a sensitive clone of CEM cells. It can be used alone as a rapid screening test in order to measure both cytotoxicity and the potential antiviral activity of large numbers of compounds. It can also be combined for thorough studies with other classic tests that detect virus production. Among these tests, a micro-method to measure reverse transcriptase activity is shown to be very useful. To illustrate the practicability of the assay, 3'-azido-2',3'-dideoxythymidine (AZT) and ribavirin are studied.