During a period of nearly thirty years we have been studying the effect of various forms of therapy in bacterial meningitis. Before the newer chemicals became available the case fatality in pneumococcic meningitis was 100 per cent in our experience and in meningitis due to Haemophilus influenzae more than 95 per cent. The use of azosulfamide and sulfanilamide moderately improved the prognosis. In a series of fifty-three cases of pneumococcic meningitis treated by one or both of these chemicals (and specific serum when available) there were nine recoveries. In treating meningitis due to H. influenzae by means of these chemicals and specific serum the results were much less encouraging. In a series of twenty-nine cases there were only two recoveries. The excellent results obtained with sulfapyridine in pneumonia due to the pneumococcus led us to try the use of this chemical in pneumococcic meningitis. This report is based on a