The widespread success enjoyed by sulfanilamide and its derivatives in the treatment of some infectious diseases has naturally called attention to possible applications in ophthalmology. Encouraging reports have already appeared in their use in trachoma by Kirk and his associates,1Loe2and others; in gonorrheal ophthalmia by Magitot and his associates,3Luis and Ricardo, Fernandez,4Willis5and others; in orbital cellulitis by Goldenburg6and Szinegh;7in abscess of the lid by Szinegh, and in herpetic corneal lesions by Kleefeld.8Experimentally, streptococcic infections in rabbits' eyes have been successfully treated with sulfanilamide by Rambo.9Little work has been done, however, on the penetration of this compound into the eye, although Marshall and his co-workers10demonstrated that it readily entered various tissues and fluids of the body. Rambo, on the basis of a single determination, concluded that it appears in the aqueous