Cytologic examination of the cerebrospinal fluid is a technically simple, yet productive, diagnostic procedure. Here is a practical guide to this method, as used in the diagnosis of different pathologies. High-quality slides depict the common cerebrospinal fluid cell types, cell anomalies in inflammatory conditions and neoplastic and non-neoplastic disorders, and cases with contaminants. It’s required reading for pathologists, as well as neurologists and neurosurgeons.