Pneumococcic meningitis has been considered an almost universally fatal disease, the mortality being about 95 per cent. Clinical observers have reported occasional cures by the use of type specific antipneumococcus serum or by the use of ethylhydrocupreine hydrochloride. These two therapeutic agents in combination have been used in a few additional cases, but the results are far from gratifying. Recoveries are so rare that they usually gain access to the medical literature. Experimenters have demonstrated that sulfanilamide has a bacteriostatic and bacteriocidal action on pneumococci both in vivo and in vitro. Rosenthal1found that the drug was quite effective in peritonitis in the mouse caused by pneumococcus types I, II and III, results which were confirmed by Long and Bliss.2Cooper and Gross3produced type III pneumonia in mice and noted that the mortality rate was decreased and the survival period prolonged in those which did succumb.