In this retrospective study on 141 HIV-positive subjects, allergy was studied by a specific questionnaire and the Phadia-Top-Test, an in vitro screening test detecting specific IgE; both were correlated to the patient's history, clinical symptoms and the treatment used. Allergy was studied in reference to HIV-negative controls and in relation to the clinical and biological subgroups of HIV patients. The application of the x2 test demonstrated a high incidence of allergy and a specific relation to the HIV infection compared to the controls as well as in relation to the clinical stage of the infection. Atopy was not specifically related to the HIV infection despite the higher frequency found in the AIDS-IKEL group. A significant number (21%) of patients with T4 > 300/μ1 considered immunocompetent presented clinical manifestations of AIDS-IKEL and 100% of these patients were allergic. A significant number (19%) of patients with T4 < 300/μ1 considered immunodeficient were asymptomatic and 75% of them were allergic. Thus allergic symptoms may transiently be the only clinical manifestations in HIV infection and possibly a co-factor for the evolution of the disease due to the immunomodulatory function of the mediators, the cytokines and the proteases released during allergic reaction.