RESUMEN
Soon after HIV (Human Immunodeficiency Virus) was discovered, its characteristics level of diversity and variability was established. So far, within HIV-1 it is known that there exist 3 main groups, 9 subtypes and at least 12 recombinant forms. Not only does this diversity affect taxonomy, but also prophylaxis and therapy for HIV infection. Numerous studies worldwide have demonstrated the influence this variability has on both diagnosis and monitoring assays as well as on the pathogenesis of HIV infection. In Argentina, from the molecular point of view, the epidemic shows a complex pattern. HIV-1 subtypes B and F have been described as well as a recombinant B/F form. Epidemiology and molecular data suggest high percentage levels and a great diversity of these recombinant forms in the heterosexual population.