THIS REPORT presents the results of the treatment of two series of infants and children with tuberculous meningitis. The first, consisting of 19 patients, was treated from May, 1947, to February, 1952, with use of a regimen of intramuscular and intrathecal streptomycin, plus oral paraaminosalicylic acid and/or thiazolsulfone (Promizole). The current series of six patients has been treated since May, 1952, with the use of a regimen of intramuscular streptomycin and oral paraaminosalicylic acid and isoniazid, without intrathecal streptomycin. Serum and cerebrospinal fluid isoniazid levels and other laboratory studies are included for the first three patients of the second series and for a fourth patient with only miliary tuberculosis, who served as a control. Success in the treatment of tuberculous meningitis has been attained by various regimens. Lincoln and co-workers, 1 in 1948, reported one of the most favorable early series, with six surviving out of seven patients, using intramuscular