51 patients with cerebrovascular diseases were examined by CSF spectrophotometry (CSF-SPE) and computerized transverse axial tomography (CTAT: EMI scanning), most cases being followed by several examinations. Specific diagnoses were detected in 98 (CSF-SPE) and 75% (CTAT) of the cases, generally by only one examination. In cases examined angiographically or by isotope encephalography, the corresponding figures were 50 and 0%. The combination of CSF-SPE and CTAT examination obviously means a breakthrough in diagnosis of cerebrovascular diseases which is naturally a prerequisite for the more rational therapy of these common and frequently disabling disorders.