Other ; Streptococcus pneumoniae infections are challenging since pneumococci have more than 90 serotypes and emergence of resistant strains has increased. Surveillance systems are essential for effective vaccine strategies and development of treatment protocols. This study aimed to evaluate the serotype distribution and antimicrobial susceptibility of S. pneumoniae causing invasive pneumococcal disease in adults (>18 years). S. pneumoniae strains were collected from 14 different centers between 2005 and 2015. Pneumococcal serogroup and serotype identification was performed using standard conventional methods. Antibiotic susceptibility testing was performed using E­test and interpreted according to the CLS I 2014 standards. S. pneumonia strains (n=346) were isolated from blood (60. 1%), bronchoalveolar lavage (19. 7%), cerebrospinal fluid (11. 0%), pleural fluid (6. 1%), and other body fluids (3. 1%). The most common S. pneumoniae serotypes were found as serotype 3 (13. 0%), 19F (12. 7%), 19A (6. 1%), 14 (4. 6%), and 6B (4. 0%). Vaccine coverage rate was 27. 4% for 7­valent pneumococcal conjugate vaccine (PCV­7), 53. 5% for PCV­13, and 62. 3% for 23­valent pneumococcal polysaccharide vaccine (P P V­23). For oral penicillin V, resistance rate was 21. 7% and intermediate resistance rate was 16. 8%. F or parenteral penicillin, 52. 6% was resistant in strains isolated from CS F (meningitis) and 0. 6% was resistant and 5. 8% was intermediate in strains isolated from other specimens. F or cefotaxime, 5. 3% was resistant and 18. 4% was intermediate in strains isolated from CS F , whereas 1. 6% was resistant and 6. 5% was intermediate in strains isolated from other specimens. Erythromycin resistance was 28. 6%. No resistance was detected to moxifloxacin but intermediate resistance was 0. 6%. Serotypes 19A and 19F exhibited higher rates of penicillin and erythromycin resistances. Since serotype distribution and antimicrobial susceptibility of clinical S. pneumoniae isolates may change in time naturally also with medical interventions likeantibiotic use and vaccination, close monitoring is essential.