The aim of the study was to determine the concentration of pneumococcal antibodies after a dose of 7-valent pneumococcal conjugate vaccine (PCV7) in 30 asplenic children between 4 months and 19 years of age. Fifteen children had received pneumococcal polysaccharide vaccine (PPV) approximately 5 years prior to vaccination with PCV7. The antibody concentrations against serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F were measured by ELISA before and after the PCV7 vaccination. Before vaccination with PCV7, the antibody concentrations were similar in children who had or had not received PPV previously. A dose of PCV7 stimulated a good immune response in asplenic patients. Prior immunization with PPV did not affect the antibody concentration after the vaccination with PCV7. In conclusion, asplenic children vaccinated with PPV may need revaccination with PPV earlier than the recommended 3-5 years after the first dose. PCV7 induces a satisfactory immune response in asplenic patients and should be considered as an alternative vaccine in that patient group.