The aim of this study was to evaluate specific IgG responses against pneumococcal serotypes 1, 6B, 14, 19F, 23F at baseline, 1 and 12 months after vaccination with the 23-valent polysaccharide pneumococcal vaccine in 89 HAART-treated HIV-infected patients, 24 antiretroviral "naïve" HIV-infected and 30 non-HIV-infected healthy subjects. Levels of specific antipneumococcal IgG and the mean fold increase in IgG levels at 1 month as well as the kinetics of antibodies along the 12 months in all groups of HIV-infected patients and healthy subjects were similar. Neither CD4 cell count at baseline nor "nadir" CD4 cells correlated with the response to the vaccine. In conclusion, the immunogenicity conferred by the polysaccharide vaccine in HIV-infected patients under HAART is at least as good as that observed in healthy subjects.