Two acute phase reactants, four cytokines, five soluble factors and lymphocyte subpopulations have been simultaneously evaluated in 16 subjects before and closely after the HIV-Ab seroconversion time. The same variables have also been determined in 50 HIV-Ab-negative high risk subjects, in 36 CDC II-III and in 30 CDC IV patients, utilizing a mixed longitudinal epidemiological model. The results show significant variations of few parameters in the early phases (increase: sCD8, beta-2-Microglobulin, sIL-2R, sCD23, Neopterin, IFN-alpha; decrease: CD4+ lymphocytes). In the course of the disease, many others parameters progressively increase (IFN-tau, IL-4, IL-6, acid-alpha 1-glycoprotein, alpha 1-antitrypsin) or decrease (B- and T-lymphocytes). Ferritin, in particular, highly increases only in CDC IV stage. These data may be useful to monitor patients during the entire course of their disease and to suggest the time elapsed from seroconversion.