Background: Meningitis is an acute inflammation of the protective membranes, the brain and spinal cord, collectively known as the meninges. It is the most common sequelae to microbial invasion of the CNS. Aim: To study the diagnostic value of lactate dehydrogenase levels in CSF in different etiology of meningitis. Material and methods: The study included fifty patients (n=50) of meningitis, on the basis of clinical findings, CSF findings and MRI brain from cases admitted in emergency, indoor medical wards and ICU of Guru Nanak Dev Hospital, Amritsar. The CSF specimens were obtained by lumbar puncture using all the aseptic precautions. The following procedures were performed on all CSF specimens: Protein, Glucose, Analysis for total and differential leucocyte count and Gram stain, and culture on blood agar and heated blood agar. Chest X-ray, and ultrasound abdomen were done, when indicated. CSF LDH was recorded by kinetic method. Results: Mean age of subjects in our study came to be 41.6±17.1 years with male predominance. Mean LDH levels in TBM were 153.97±34.46 IU/L, in PM 238.25±32.06 IU/dl and in viral meningitis were 46.71±11.96 IU/L. On comparison the results were statistically significant. Overall, elevated LDH levels show 88% sensitivity. Conclusion: CSF LDH is markedly raised in pyogenic meningitis, moderately increased in tubercular meningitis and marginally increased in viral meningitis and the difference between the values is statistically significant. Hence CSF LDH may be sensitive biochemical markers for diagnosing and differentiating pyogenic, tubercular and viral meningitis. Key words: meningitis, cerebrospinal fluid, LDH