We assessed the immunogenicity, safety and tolerability of heptavalent pneumococcal conjugate vaccine (PCV7) administered three, five and 11 months post-natally to 46 pre-term (PT) and 46 full-term (FT) infants. After each dose, there was no significant difference between the groups in antibody levels for any of the vaccine serotypes. After the second dose, the majority of subjects in both groups showed titres of > or =0.35 microg/mL, whereas an antibody concentration of > or =1.0 microg/mL was usually reached in both PT and FT infants after the third dose. Safety and tolerability was also similar in the groups. These findings support the use of the simplified schedule that includes three doses of PCV7 in both PT and FT infants, and suggest that this may reduce costs, as well as problems related to vaccine supply and administration.