Aggressive treatment has been advocated for the management of primary HIV infection (PHI), but the composition and the optimal duration of therapy are still to be determined. In addition, time to undetectable viral load (VL), rate and duration of VL suppression as well as subsequent therapeutic choices remain issues widely debated. We evaluated the rate and duration of VL suppression in 12 consecutive patients with PHI given triple-drug treatment with zidovudine, lamivudine and indinavir (highly active antiretroviral therapy, HAART) at onset of the acute illness and subsequently switched to a simplified 2-NRTI-based regimen once VL suppression was maintained for at least 6 months. Throughout the study, no patient discontinued treatment because of symptoms attributed to the study medications. In the study population, undetectable VL was achieved after a median of 84 days (range: 67-135) on HAART and was maintained for a median of 194 days (range: 179-205) before simplification. After switching to simplified maintenace, undetectable VL was maintained in all patients for at least 6 months. Only one patient experienced virological failure, plasma HIV-RNA remaining suppressed for a median foliow-up of 33 months (15-54) and T-CD4+ being steadily higher than 500/mL in the remaining patients. Our results suggest that simplification of HAART in patients promptly treated during PHI and maintaining undetectable VL for at least 6 months before simplification may be a valid option capable of controlling viral replication and maintaining an optimal immunological profile for a prolonged time.