Abstract 1.1. The activity of 3′,5′-dibromosulfanilanilide has been compared to that of sulfadiazine and sulfathiazole against such organisms as G. tetragena, Streptococcus agalactiae, Str. viridans, L. monocytogenes, H. ducreyi, Brucella abortus, Brucella melitensis, Brucella suis, and A. bovis. 2.2. A greater bacteriostatic effect and a far greater bactericidal effect was exerted by 3′,5′-dibromosulfanilanilide than by sulfadiazine or sulfathiazole against these organisms.