Producción Científica The World Health Organization (WHO) has recently released updated guidelines for HIV diagnosis that recommend serum antibody testing by either EIAs or rapid tests and that encourage the identification of unrecognized HIV infections [1]. However, this approach may fail to identify subjects with acute infection. In consideration of the potential public health benefits of not missing individuals in the most contagious phase of infection, implementation of routine HIV RNA screening has been suggested [2]. We want to stress that there are other situations in which viral load is detectable in the absence of reactive antibody tests and in which the introduction of nucleic acid testing may be beneficial. This is the case for HIV-infected subjects in whom specific antibody responses are absent, as for the case reported here. Fondo de Investigaciones Sanitarias (project CP05/00300) Fundación para la Investigación y Prevención del Sida en España (project 36483/05) Fundación Investigación y Educación en Sida.RIS (project ISCIII-RETIC RD06)