Background: Meningitis is a life-threatening inflammatory disease of the meninges. If not treated, bacterial meningitis can lead to brain swelling, permanent disability, coma and even death. To reduce the morbidity and mortality related to bacterial meningitis, it is important to differentiate septic meningitis from aseptic meningitis during the acute phase of the disease. Objectives: To evaluate the role of serum procalcitonin (PCT) in the differential diagnosis of septic and aseptic meningitis and to evaluate serum procalcitonin as a prognostic marker for meningitis severity and the success of meningitis treatment plan. Methodology: This study was conducted on total number of 63 subjects that were subdivided into three groups, 25 patients with septic meningitis (groupI), 20 patients with aseptic meningitis (group II) and 18 age and sex matched subjects without CNS diseases as control (group III). All subjects were subjected to full history taking, clinical examination and laboratory investigations. Serum PCT was measured for all the study subjects using ELISA method. Results: Serum PCT at cut off level >0.180 ng/dL clearly distinguished patients with meningitis from control group (P-Value <0.001) while at cut off level >0.492 ng/dL differentiate patients with septic meningitis from those with aseptic meningitis with 100% sensitivity and specificity (P-Value <0.001). All cases that had bad outcome had higher level of PCT than cured cases even after treatment. The most frequently detected organisms in septic meningitis group were St. pneumoniae (28%), Staph. aureus (16%), K.pneuominae (16%), E. coli (12%) and N. meningitides (8%). About 85% of isolated Enterobacteriaceae species were potential ESβLs-producers. 25% of K. pneumoniae isolates were MβLs-producing, E.coli was 100% sensitive to Carbapenems group and Amikacin while K.pneumoniae showed only 75% sensitivity to Carbapenems group and 100% of S. aureus isolates were MRSA. Sensitivity to the new therapeutic drugs was 100% for linezolid and teicoplanin for S. aureus and St. pneumonia. The most frequently detected organisms in aseptic meningitis were Cryptococcus neoformans (5%) and Herpes simplex 1/2 viruses (10%). Conclusion: Serum PCT level can be used as a diagnostic and prognostic marker in patients with meningitis. It can also differentiate between septic and aseptic meningitis