- Background. Exposure to tobacco smoke is associated with higher risk of Streptococcus pneumoniae and Haemophilus influenzae infection. The aim of this study was to determine the influence of smoking and exposure to tobacco smoke on S. pneumoniae and H. influenzae carriage rates in children and their mothers. Patients and methods. We performed a cross-sectional surveillance study of nasopharyngeal and oropharyngeal carriage of S. pneumoniae and H. influenzae in 208 children aged <60 months and their mothers. Smoking exposure and medical history were recorded. Carriage rates for children and their mothers in nasopharyngeal and oropharyngeal specimens were analyzed on the basis of smoking exposure. Results. The S. pneumoniae carriage rate was higher among children exposed to smoking than among nonexposed children (76% vs. 60%; P =.016). Exposed children more frequently carried S. pneumoniae serotypes included in the conjugate 7-valent vaccine, compared with nonexposed children (49% vs. 30% of all S. pneumoniae-positive nasopharyngeal cultures; P =.02). Carriage rates of S. pneumoniae were higher among mothers who smoked than among mothers exposed to smoking and among nonexposed mothers (32%, 15%, and 12%, respectively; P =.03). There were no differences in H. influenzae carriage rates between children and mothers from smoking and nonsmoking families. Conclusions. Exposure to tobacco smoke increased S. pneumoniae carriage rates in general and for carriage of serotypes included in the conjugate 7-valent vaccine in particular in children. Smoking mothers had a higher S. pneumoniae carriage rate than did nonsmoking mothers. Smoking or exposure to smoking did not increase H. influenzae carriage rates in children and mothers.