In all biological systems growth is defined as increase of chemical compounds. Bacteria can achieve to balanced growth if they are growing in a medium, which are completely adapted to it. Clostridium chauvoei, (Clostridium feseri) is an anaerobic, spore forming, motile, and polymorph bacteria, which its size varies from 0.5-1 to 3-8 micron and could be observed as individual bacterium, diplo, and rarely streptococcus. Blackleg is a fatal disease of young cattle. It produces an acute local infection, and the resulting blood poisoning leads to rapid death. Clostridium chauvoei and, less frequently, Clostridium septicum are the most commonly responsible organisms. Vaccination is the only effective means for controlling of blackleg disease. Several kinds of vaccine are available commercially. It is 4 decades that blackleg vaccine is produced in Razi institute and because of enhanced demand of country, decision was made to improve the production procedure of this vaccine using large-scale fermenter, so the aim of this study was adaptation of Clostridium chauvoei to growth and proliferation in fermenter for preparation of a potent vaccine. Accordingly attempts were made to prepare and formulate the ingredients in order to obtain high yield of Clostridium chauvoei in culture medium by fermenter. All experiments were done in two sets: A-growth in glass bottles using conventional culture medium and B-growth in fermenter using conventional culture medium similar to A and also enriched culture medium. Results showed high yield of Clostridium chauvoei suspension in fermenter after 10 hours, using enriched culture medium (more than 1,480,000,000 organisms/ml), but no significant changes was obtained in glass bottles conditions comparing to the fermenter conditions. The safety and potency of the prepared vaccine was determined in sheep and guinea pigs according to British pharmacopoeia (veterinary) with satisfactory results. Since this research has been successfully done in Razi research institute, so the mono valent inactivated blackleg vaccine, using the enriched culture medium is currently producing by fermenter and is used for immunization of cattles in Iran.