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SEVERAL methods for isolatingBrucella from heavily contaminated specimens have been described in the literature. The Royal Commission on Malta Feverl recommended the addition of anti-brucella serum to the specimen and subsequent culture of the agglutinated bacilli which were supposed to settle out on standing. Amoss and Poston2 modified this method using crystal violet infusion agar, which had been recommended by Huddleson.3 Gould and Huddleson altered the concentration of gentian violet,4 and later the composition of the basic agar was radically improved.5 The difficulty encountered by various workers in the isolation of Brucella from feces or other heavily contaminated material was partly caused by the resistance of Escherichia coli to the dyes, the length of time needed by the various species of Brucella to appear on the media and/or the spreading growth of such genera as Proteus and Bacillus.The value of tyrothricin and sodium azide was therefore investigated in this connection and resulted in a relatively simple inhibitory medium which allowed the growth of Brucella suis. MATERIALS AND METHODSStrain-The culture of Br. suis which was used predominantly in this *Studies