Considering the lack of complete agreement of viewpoints concerning the heterogeneity of ABB indices of CSF at various levels along the cerebrospinal axis, an attempt was made to elucidate this problem. For this purpose 82 patients suffering from diseases causing increased intracranial pressure and spinal pain were examined. A total of 262 samples of CSF was taken from cisterna magna and from the lumbar region of the subarachnoid space. In accordance with the degree of severity of clinical symptoms resulting from increased intracranial pressure, the patients examined were divided into five groups. The results of examination show irregular differentiation of samples of CSF which is related to the clinical state of the patients examined. On the basis of the authors experience and data from medical literature an attempt was made to explain this phenomenon so complicated in its aetiology.