The antibody production by HIV-infected adults after two vaccinations with conjugated pneumococcal vaccine (CPV) and consecutive vaccination with polysaccharide pneumococcal vaccine (PPV) was studied. Thirty days after the second CPV, the geometric mean antibody concentrations (GMC) against pneumococcal polysaccharide serotypes (PPS) 6B, 14 and 19F were significantly lower in the group HIV-infected individuals with <200x10(6)/l CD4(+) T lymphocytes (group 1) than in the group with >/=200x10(6)/l CD4(+) T lymphocytes (group 2) and healthy controls. Thirty days after PPV vaccination the GMC against PPS 6B, 14, 19F and 23F in group 1, and against 6B and 19F in group 2, were significantly lower compared with healthy controls. Both in HIV-infected and in healthy individuals who received CPV and PPV the postvaccination GMC against PPS 14, 19F and 23F were higher compared with historical controls who were not previously immunized with CPV but only received PPV. We conclude that the antibody response to CPV is impaired in HIV-infected individuals. Higher antibody concentrations were achieved in HIV-infected and healthy individuals after sequential vaccination with CPV and PPV compared with PPV vaccination alone.