Antibody responses in recent human immunodeficiency virus (HIV) seroconverters to 2 vaccines were studied. Twenty patients infected with HIV for < 18 months and 15 HIV-seronegative controls were vaccinated with the 23-valent pure polysaccharide pneumococcal vaccine and the Haemophilus influenzae type b (Hib) capsular polysaccharide diphtheria CRM197 protein toxoid conjugate vaccine in separate arms. Despite increased levels of total serum IgG, recent seroconverters and controls showed similar specific IgG responses for 6 of 7 antigens. Baseline levels were equivalent in both groups, as were peak levels of IgG at 1 month to conjugated polysaccharide (Hib), delayed-type hypersensitivity, and pneumococcal capsular serotypes 4, 6B, 12F, and 14. At 6 months, IgG levels were similar for 4 of 7 antigens. Antibody responses to pure pneumococcal capsular polysaccharides and to a protein recall antigen were most often similar among recent seroconverters and seronegative controls. Both total levels and fold-rises of IgG to the Hib conjugate were similar in the 2 groups. Immunization of HIV-infected patients soon after seroconversion rather than later appears to improve antibody responses.