One hundred thirty-two children with tuberculous meningitis were admitted over a period of 1 year to the L. T. Municipal Medical College Hospital, Bombay. It was found that the most important single factor influencing the prognosis was a developing hydrocephalus. Of the 132 patients, 50 showed hydrocephalus and had to be operated. The operation markedly improved the sensorium, the vision and the neurological deficit of the patients. A plea is made for early detection and treatment of hydrocephalus.