Objective To investigate the antimicrobial susceptibility of Streptococcus pneumoniae carried in the nose among children in Beijing and the distribution of serotypes,and to analyze the risk factors for nasal carriage of penicillin non-susceptible S.pneumoniae.Methods A disk diffusion test was applied to detect the antimicrobial susceptibilities of S.pneumoniae to erythromycin,trimethoprim-sulfamethoxazole,chloramphenicol and tetracycline.The E test was applied to determine the minimal inhibitory concentrations of penicillin,cefuroxime,cefotaxime,augmentin and imipenem.S.pneumoniae isolates were serotyped by the Quellung reaction.Results S.pneumoniae that was resistant to penicillin or cefuroxime was not found,but S.pneumoniae intermediate resistant to penicillin and cefuroxime accounted for 8.2% and 2.1%,respectively.All of the isolates were susceptible to cefotaxime,augmentin and imipenem.S.pneumonia that was resistant to erythromycin,trimethoprim-sulfamethoxazole and tetracycline were extremely numerous,accounting for 72%,70% and 79%,respectively.Five serotypes(19,6,14,23,17)accounted for 54.7%,and nontypables accounted for 20.6% of all the S.pneumoniae.Previous history of otitis media was a risk factor we found for nasal carriage of penicillin non-susceptible S.pneumoniae.Conclusions Continued surveillance of the antimicrobial susceptibilities of S.pneumoniae is necessary.A larger scale investigation is needed to identify if the 7 or 9-valent conjugate pneumococcal vaccine is appropriate for Chinese children.