One million cases of bacterial meningitis are estimated to occur and 200000 of these die annually. Streptococcus pneumoniae is the leading causative agent in Egypt. Purpose : To address the difference between aseptic and bacterial meningitis as regards causative agent , risk factors and predict the value of diagnostic model in differentiation of bacterial from aseptic meningitis methods adults (aged 18 years and older) admitted to Embaba fever hospital with clinical diagnosis as meningitis during 2012 were recruited for the study they were subjected to clinical examination , laboratory investigation as well as CSF bacteriological and serological analysis and application of bacterial meningitis score results 90 patients (47 male and 43 female ) were included . About 25.5 % of cases were infected with acute bacterial meningitis and 74.5 % were infected with aseptic meningitis. In this study ABM was caused by streptococcal pneumoni (65.2%), H influenza (26.1%) and N.meningitidis (8.7%). ABM showed insignificant association with age, sex and seasonal variation but significant with low socio economic state, number of smoker in families and residents in urban areas, increase CRB, ESR and CSF turbidity in bacterial group. Over all accuracy of the score was (90%) Conclusion this study high lights several difference between aseptic and bacterial meningitis in adults and concluded that quick and simple score will be valuable tool in the diagnosis of meningitis.