The total protein content and the protein fractions (paper electrophoresis) were determined in the CSF of 28 patients with degenerative diseases of the CNS. The diagnosis and the results obtained are presented in table 1. An increase in the β-globulin content of the CFS was the main change found. It was observed in 12 cases. The observation confirms the findings of other authors. The data were discussed and it was shown that the severity of the changes in the metabolism of nerve cells and the extension of the process are more able to explain the increase in the β-globulin content of the CSF. The occurrence of an increase in the β-globulin content of the CSF was related to the localization and extension of the disease process within the CNS and not to the etiology. The distribution of the cases according to the possible site of the lesion in the CNS shows that the increase in the β-globulin of the CSF was more frequent when signs of encephalic involvement were patent (table 2).