Abstract: The present invention relates to a method for the preparation of a swine dysentary subunit vaccine. The swine dysentery subunit vaccine is composed of antigenic material harvested from the surface of an anaerobic spriochete, Treponema hyodysenteriae. The bacterial cells, previously grown in large volume (5-7 liters) in a bench-top fermentor, are harvested by centrifugation and washed vigorously in phosphate buffered saline. The bacterial cells are then removed by a second centrifugation and the supernatant retained. The supernatant contains a salt extract consisting of the antigenic material used in the vaccine. Once harvested, the salt extract is concentrated 100X. The salt extract has been shown to be immunogenic in pigs. Five to six week old pigs are hyperimmunized intramuscularly (IM) with the salt extract. Pigs vaccinated with the salt extract are protected against infection with Treponema hyodysenteriae.