Background. Bacterial meningitis is a severe, potentially life-threatening infection that is associated with high rates of morbidity and significant disability in survivors. Overall mortality rates related to bacterial meningitis of around 20% to 25% have been reported by major centers. Our study is to determine the incidence rate and etiology of childhood bacterial meningitis in Ulaanbaatar, Mongolia.Methods. From 2002-2010, a total of CSF 433 and blood 544 samples were obtained from children age 0-5 years old. The following diagnostic criteria for bacterial meningitis in children aged 0-5 years were used: questionnaires, clinical signs and positive CSF culture and/or CSF antigen test results positive N. meningitis serogroups B, A, C, Y, and W-135, Hib or S.pneumonia; and/or positive CSF PCR results; and/or positive blood culture results with CSF pleocytosis (WBC count, >10 cells/uL). Pathogens were identified and serotype or serogroup with standard methods in the reference microbiology laboratory. Detection of bacterial pathogens with a multiplex and real-time PCR assay.Results. From totally 544 suspected cases had been detected bacterial meningitis in 260 (47, 8%) cases and sepsis in 111 [20,4%] cases respectively. The disease in the 83 [27.1 %] etiologically diagnosed patients was due to H.influenza, S. pneumonia was in 71 [36, 4%] cases and N.meningitis in 111 [24, 7%] respectively. Among the positive samples 80.6% (129/160) the specific serogroup and/or serotypes for N.meningitis serogroups A was available in 22(35, 4%) cases, for the Hib 52(96, 3%) and 6(40%) for the S.pneumoniae 7 serotype. The real time PCR assay was more sensitive for detection of meningitis pathogens than conventional methods (culture and latex agglutination), 19% in comparison with latex agglutination (p<0.0026) and by 39% in comparison with culture (p<0.001). Bacterial meningitis was identified 70.0 in 2004 among population, but it reduced until 5.0 in 2009. The incidence of Hib meningitis was 2002-2005y, N.meningitis and S.pneumoniae meningitis were 2006-2008y, S.pneumonia meningitis was more higher 2009-201 Oy comparing with other pathogens.Conclusion. N.meningitidls, S.pneumoniae H.influenzae type b are the leading causative agents of childhood bacterial meningitis in Ulaanbaatar, and the incidence rate is higher than what were reported in other Asian countries.