The objective of this chapter is to introduce the cerebrospinal fluid examination. Analysis of the cerebrospinal fluid (CSF) is of diagnostic importance in conditions like meningitis or primary/metastatic tumor of CNS with CSF involvement. CSF is usually obtained by lumbar puncture (LP) using an LP needle under strict aseptic conditions. This chapter covers the method of collection and examination of cerebrospinal fluid. Examination of cerebrospinal fluid includes physical examination, microscopic examination, biochemical evaluation, and microbiological examination. Microbiological examination helps to identify the causative agent in cases of meningitis. The microbiological examination includes Gram-stain, AFB stain, serological examination, culture and sensitivity and PCR, etc.