Objectives: To determine the level of serum procalcitonin, blood leukocyte count (TLC) and C-reactive protein (CRP) in children with bacterial and non bacterial meningitis and document their efficacy in differential diagnosis. Also described are procalcitonin levels variation during treatment. Methods: From March 2005 to February 2008, we evaluated 38 clinically suspected meningitis patients in the paediatric departments, Al-Jedaany Hospital, Jeddah, KSA, for Serum procalcitonin, CRP, TLC and Lumbar punctures and CSF analysis. Patients were classified into bacterial meningitis group I (18) and non bacterial meningitis group II (20). Results: Serum PCT levels were significantly higher in bacterial meningitis (BM) {mean 4.8 ± 3.85 ng/ml (2.9- 11.6)} compared with non bacterial meningitis (NBM) {mean 0.38 ± 0.25ng/ml(0.31-0.61)} {P< 0.001}. Mean of all CSF parameters, TLC {15,000 ± 2,900 cell/ml(BM) & 9,500 ±1,105 cell/ml(NBM)}and CRP {20 ± 6.8 mg/l (BM) & 12.5 ±12.0 mg/l(NBM)}showed a zone of overlapping between the two groups. There is a positive correlation between serum PCT, TLC and CRP in bacterial and non bacterial meningitis cases but this relation becomes highly significant with bacterial meningitis positive group. Day 3 and day 6 treatment serum PCT was less than on admission levels (P<0.001). Conclusion: PCT can be used in the early diagnosis of bacterial meningitis and may be a useful adjunct in differentiating bacterial and non bacterial meningitis than CRP or TLC and diminishing the value of lumbar puncture performed 48-72 hours after admission to assess treatment efficacy