We prospectively studied 462 individuals of different age groups attending to outpatient clinics in Istanbul to assess the nasopharyngeal colonization rate and the antibiotic resistance patterns of the isolated haemophilus strains. Prevalence of Haemophilus influenzae in patients under 5 years of age and in patients over 5 years of age was 76.9% (253/329) and 58.6%(78/133), respectively. The antimicrobial susceptibility to chloramphenicol, ampicillin, cefuroxime and ceftriaxone was determined by microbroth dilution tests. Of 106 H. influenzae isolates, 24.5% were resistant to ampicillin, 8.5% to both ampicillin and cephalosporins, and 4.7% to all four antibiotics. Twenty point eight percent of the strains produced beta-lactamase. These results emphasize the emerging resistance to ampicillin among H. influenzae strains in Turkiye and urge to discuss efficacy of the first line agents in H. infections.