Three successive CSF investigations make it possible to identify even the smallest amount of cerebrospinal fluid (CSF) in cases of otorrhea and rhinorrhea: 1. Immunological identification of beta 2-transferrin. 2. Laboratory fluorescein identification. 3. Endoscopic fluorescein detection. As a screening procedure the beta 2-transferrin identification method is always used as the first step towards clarifying a suspect liquorrhea. In addition both fluorescein tests are used for the diagnosis depending on the result of the beta 2-transferrin identification and further measures. As a result of recent practical experience special attention is paid to the test analyses; the various possibilities of taking samples as well as mailing them. A newly developed diagnostic plan of procedure should (by using practical examples) underline the clinical significance. This study describes the most up-to-date level in CSF diagnosis and demonstrates that, when combined with a corresponding X-ray investigation, a much more exact range of indication for the surgical treatment of fractures of the base of the skull and CSF leaks is possible.