Streptococcus pneumoniae is the main etiologic agent in community-acquired pneumonia, meningitis in adults and acute medium otitis in children. Our aim was to study antimicrobial susceptibility and serotypes of Streptococcus pneumoniae strains isolated in our medium. We evaluated 83 strains in a period of two years: 41% of the strains were invasive, and 47% of the strains were resistant to penicillin, 42.1% to erythromycin, 16.8% to cefotaxime, 34.9% to tetracycline and 16.8% to chloranphenicol. All studied strains were susceptible to vancomycin. We found 28 different serotypes. The most frequently found serotypes were 19, 6, 9, 23, 3, 15, and NT. The S. pneumoniae strains which showed the highest penicillin resistance belong to serotype 19. Multiresistant strains belong to serotypes 19, 6, 23 and NT.