Introduction: Bacterial meningitis is a common clinical problem among the infants and children in Bangladesh. Delay in distinguishing bacterial from non-bacterial meningitis may terminate into fatal consequences. Aim of the study: The aim of the study is to evaluate the impact of bacterial antigen detection in cerebrospinal fluid (CSF) in the diagnosis of meningitis. Materials & Methodology: This cross-sectional study was carried out in the Department of Paediatrics, Bangabandhu Sheikh Mujib Medical University (BSMMU) and Department of IImmunology, Bangladesh Institute of Research and Rehabilitation in Diabetes, Endocrine and Metabolic disorders (BIRDEM). Subjects were recruited randomly from the Department of Paediatrics, BSMMU, Department of Paediatric, Dhaka Medical College Hospital (DMCH) and Paediatric Medicine Unit, Dhaka Shishu (Childern's) Hospital during 1996 to 1997. A total 40 subjects clinically suffering from meningitis were selected randomly with inclusion and exclusion criteria.All data were analyzed by using SPSS program (SPSS for Windows, Release 7.5) and expressed as mean ± SD or in frequency or percentage unless mentioned otherwise. Results: The bacterial antigens were positive only in the bacterial group (Haemophilus influenzae 42.1%, p = 0.001: Streptococcus pneumoniae 21.1%, p = 0.069; Nesseria meningitidis group B/Escherechia coli Kl 5.3%, p=0.645 and Nesseria meningitidis group C 5.3%, p=0.645). For all the three meningitis of bacterial antigen (p = 0.053), multiple regression showed significant relation in age, history of respiratory tract infection, drug history, neurological deficit, total count, CSF cell count, CSF glucose, CSF protein, gram stain and AFB stain, CSF culture and bacterial antigen. Conclusion: Bacterial antigen has positive impact only in Bacterial meningitis in the present study. Detection of bacterial antigen in CSF helps to separate bacterial from tubercular and viral meningitis. In short, bacterial antigen in CSF alongwith biochemical and cytological features of CSF are very much helpful in distinguishing different types of meningitis and their appropriate management.