The objective of this study was to identify and define a cohort of HIV-1-infected individuals with the ability to suppress HIV-1 replication naturally (patients with undetectable viral loads for at least 2 years without antiretroviral drugs). Proviral DNA ranged from one to 74 copies/10(6) peripheral blood mononuclear cells, with the mean value lower by 1-2 logs than long-term non-progressors. This ability to control HIV-1 viral replication naturally has led us to refer to them as natural viral suppressors.