This study was aimed to define the carriage rates for Streptococcus pneumoniae in a given population in Ankara and also to determine the serotypes and penicillin resistance of these strains. Oropharyngeal swabs were taken from a total of 661 children aged between 0-11 years and living in a province of Ankara between January 1995-January 1997. Serotyping was performed by detection of the Quellung reaction. The isolates were screened for penicillin susceptibility by the agar dilution method according to the guidelines of NCCLS. The total rate of pneumococcal carriage in the study population was 23.90% and the isolation rate was found to be statistically associated with age, being higher in small children. Among the 158 S. pneumoniae isolates, the most prevalent serotypes (in order of frequency) were 6, 19, 9, 23, 3 and 14. Penicillin susceptibility was examined in 120 of the isolates. 55 of them (45.83 %) were susceptible, 53 (44.17%) were intermediately and 12 (10.0%) were highly resistant to penicillin. Evaluation of the results showed that serotypes 6, 14 and 23 were those most often associated with penicillin resistance. The significant rate of isolation of penicillin-resistant pneumococci in healthy carriers points to the importance of active immunization in risk groups and also the importance of the rational use of antibiotics to limit the spread of resistant strains.