A freeze-dried Brucella vaccine has been developed which can be issued with all the usual guarantees, e.g. 60 x 10⁹ viable organisms per dose viable for an extended period. This vaccine has been prepared in concentrated form which makes it possible to reconstitute the contents of one ampoule into a number of doses. Such a vaccine is eminently suitable for use in Southern Africa especially in the more remote areas. Concentration by means of carboxy-methyl-cellulose of the organisms grown in aerated liquid culture increased the dosage per ampoule and the survival rate after freeze-drying and during storage.