Antiretroviral drugs already registered or currently in clinical trials are shortly described, including dideoxynucleosides, non-nucleoside reverse transcriptase inhibitors, protease inhibitors, tat inhibitors and antisens molecules. In a second part, the treatment of patients with the nucleosides already on the market or in a pre-registration phase is reviewed, on the basis of an analysis of available phase III clinical trials. The third part describes the strategy of clinical trials and explains why "surrogate markers" including markers of viral replication cannot yet be the main criteria to evaluate the efficacy of a new drug in a phase III trial.