Book excerpt: The cerebrospinal fluid (CSF) is an invaluable diagnostic tool in clinical neurology, not only in the evaluation of inflammatory, degenerative, and malignant diseases of the nervous system, but also in the diagnosis of all forms of cerebral and subarachnoidal bleedings. The CSF can be easily obtained by lumbar puncture and a set of basic analyses can be conducted using relatively simple laboratory methods. By combining different CSF parameters, a wide range of diagnostic entities can be identified. However, properly interpreting the test results requires a high level of expertise and cannot be achieved by just reporting on individual analytic values. This book covers essential aspects of cerebrospinal fluid analysis and its use in the diagnosis of common neurological diseases. The first part addresses preclinical aspects such as the history of CSF, as well as the anatomical, physiological, and biological background of this valuable fluid. In addition, CSF collection, its preanalytical and methodological implications, and the increasing number of disease-specific markers in CSF are discussed in detail. Lastly, CSF analyses are put into context with clinical syndromes, demonstrating their diagnostic value in neurological clinical practice. Cerebrospinal Fluid in Clinical Neurology helps readers understand the preanalytical and analytical aspects of CSF diagnostics and offers a valuable reference guide for interpreting CSF results during the clinical work-up for neurological patients.