With a retrospective study of invasive pneumococcal disease (IPD) surveillance data representative for approximately 25% of the Dutch population (1275 hospitalized cases) over the period June 2004-June 2006 prior to the implementation of the 7-valent pneumococcal conjugate vaccine (PCV7), the aim was to provide baseline data on IPD for the interpretation of changes after implementation of conjugate vaccines. The IPD incidence peaked in 3-5-mnth-olds (63 cases per 100,000 persons yearly) and increased in adulthood, particularly after the age of 60yrs, from 26 cases in 60-64-yr-olds to 97 cases per 100,000 in persons > or =90yrs. Beyond the age of 4yrs, 19% of IPD patients were immunocompromised, and this considerable percentage may have implications for vaccine efficacy.