Prior to the advent of chemotherapy, the mortality of influenzal meningitis varied from 90 to 100 per cent. The status of the disease has been altered considerably by the use of sulfonamides and type B anti-influenzal rabbit serum. The introduction of streptomycin marked another advance. This paper is based on the use of streptomycin in a series of 90 cases of influenzal meningitis. The 90 cases in this series were consecutive and were seen between Feb. 2, 1946, and July 1, 1949. CLINICAL ASPECTS Most of the patients presented the typical picture of meningitis. Individual patients showed considerable variation in the severity of the disease, but most of them appeared critically ill. As is well known, this form of meningitis is essentially a disease of infants and young children. Table 1 shows the age distribution in this group of cases. The duration of illness before treatment with streptomycin varied from