From 1924 to 1938, 9920 autopsies were carried out in our institute; from 1955 to 1969 there were 37 784 dissections. Among the former 132 cases of tuberculous meningitis (tb. m.) were observed (1.33%), among the latter there were only 74 (0.20%). This decrease in frequency to about 1/7 is statistically highly significant; by standardization to 0.62 it has come down to 0.20% but still remains significant. The marked predominance of tb. m. in males as compared to females (2:1) that was noted in former autopsies is no longer noticeable. With regard to age distribution, a statistically warrented decrease exists only for the age group from 0 to 9 years. From the mortality graph (the dying age being identical with that of affection before the era of chemotherapy) it can be seen that while the peak during childhood has now disappeared, it is only slightly demonstrable during early adult age (as a result of the retarded primary infection). The rise in the curve indicates the deteriorating prognosis with increasing age, with the peak between 60 and 70 years accounting for the importance of miliary tuberculosis of old age for tb. m. Due to therapeutic measures, there is now an increase in the number of chronic tb. m. cases which are productive in their histological picture. As previously, tb. m. at present develops in about half of the cases in the course of miliary tuberculosis. The frequency of early generalization has significantly decreased, while that of miliary tuberculosis of old age has increased. In our examination material tb. m. without further manifestations of tuberculosis has become provable only since the introduction of chemotherapy. Errors in clinical diagnoses have increased from 12.9 to 54%. The decrease of tuberculomata of the central nervous system from 0.17 to 0.013% is also statistically highly significant in our examination material. Apart from the change of the examination material, this decrease in frequency is largely due to prophylactic BCG vaccination and tuberculo-static therapy. Both of them have brought on the rapid advances in tuberculosis epidemiology that started with the turn of the century and resulted mainly in shifting tuberculous primary infection to higher ages and, at the same time, markedly reducing the contagion of tuberculosis.