The study is based on the observations concerning to 45 patients with leprcmatcus Jeprosy. The test of Mitsuda was negative in all of them. Alcohol-acid fast bacilli were found to be present in 6 cases in cutaneous lesions and/or in nasal cavity. The study of the CSF proteins comprised the determination of the total protein content and the analysis of the proteins fractions, the latter by papel strip electrophoresis. For each patient it was studied one sample of CSF, collected from the cisterna magna and normal concerning to its physics and cytologic properties; complement fixation tests for syphilis and cysticercosis were negative in all samples. For comparison purposes other data were studied: 1. the total protein content of blood serum and its protein fractions, the latter by paper strip electrophoresis also; 2. the age of the patients; 3. the probable time of disease. Results are presented in the table 2. The total concentration of CSF proteins was normal in 42 patients; it was slightly increased in three cases. Changes in electrophoretic pattern of CSF proteins were verified in several cases. The most frequent change was the increase of the y-globulin fraction (14 cases). Its occurrence in this form of the disease was related in a previous former study; the present data confirm such observation. The data discussed in this study show that the increase in the CSF y-globulin is probably related to change in the protein pattern of blood serum. It seems to be secondary to the increase of the y-globulin fraction in the latter.