Introduction: Bacterial meningitis is a severe infection with a high mortality rate. Although conscripts are vaccinated against meningococcal meningitidis, cases of the disease have been reported sporadically among this high-risk group. The aim of this study was to determine the etiology of bacterial meningitis in this particular group.Material and Methods: In order to find out the etiology of bacterial meningitis in patients, we included four military hospitals in this study. For isolation of the bacterium, different media (i.e. Mueller Hinton agar, Trypticase Soy agar and Thiyer Martine agar, enriched by some additives) were used as well as standard bacteriological methods. From each sample, two smears (wet and dry) were prepared. If PMN was not observed in the wet smear, the sample was centrifuged for 5 min in 10000 χ g, in lab temperature and then the smear was once more prepared as mentioned above. In addition, from the CSF samples, (Mueller Hinton agar, Trypticase Soy agar and Thiyer Martine agar) were inoculated to each medium. Next, the plates were incubated at 37 C and 3% CO2 atmosphere for 24- 48 hours. Based on biochemical reactions (i.e. Catalase, Oxidase, Coagulase, Manitol Salt agar, Bacitrasine, Optocin, Bile Solubility, Glucose and Maltose), the organisms were identified.Results: In this research, 100 samples of CSF were collected in aseptic condition from meningitis patients. The results of this study indicated that 63% of the patients were male and 37% of them were female. 50% of the patients were dependants, the rest were retirees and employees. Conscripts constituted only 8% of the patients. In 28% of the patients CSF, the bacterial growth was positive, and in 72%, it was negative. Bacteriological study revealed that in 5 out of 8 Patient, Niesseria meningitidis were isolated. In one patient Neisseria sica and in 2 patients no bacterial growth were detected in CSF. In one of the patients recurrent meningococcal meningitidis was seen and in 10 patients, Streptococcus pneumonia were isolated with age older than 55 years. In addition, patients with meningitis after Lumbar Trauma, Staphylococcus coagulase negative, Pseudomonas aeroginosa and E. coli were isolated too.Discussion: In this study, 28% of suspected cases of meningitis were positive in culture media. This figure was 4.7% more than the ones previously reported; perhaps this is related to the culture method. Only 5 cases (17.8%) of Neisseria meningitidis were isolated from the suspected patients, who were Conscripts, and there was complement deficiency in three out of the 5 cases. However, these Conscripts had been vaccinated against Niesseria meningitidis. Further studies must be carried out to obtain more data. Vaccinating dependants against Streptococcus pneumonia is necessary because 35.7% of the meningitis cases were related to this organism.