Confidence in the efficacy of using antiretroviral drugs to treat HIV infection has grown in the past year as a result of the prolonged survival of those randomly allocated to receive an additional drug in comparative controlled trials. HIV remains, however, the only serious infectious disease for which antimicrobial treatment is deliberately delayed. This is because infected subjects can often be symptomless for more than a decade in the absence of any treatment, and results from trials with the nucleoside analogue reverse transcriptase inhibitor zidovudine have failed to show any evidence for extended survival in those beginning treatment early compared with those who deferred treatment. The new confidence in currently available treatments, and in the prospects for new ones, inevitably leads to renewed questioning of the current strategy of waiting for signs of immune deficiency before electing to intervene. A new randomised controlled trial comparing strategies of early and deferred treatment is required to assess whether the time has come for intervention immediately after HIV has been diagnosed.