This study was done to characterize diversity in 10 Brachyspira hyodysenteriae isolates in Korea. The isolates were compared with 14 well-characterized non-Korean strains of various Brachyspira species. All Korean isolates showed strong beta haemolysis and had blunt cell ends with 7-14 periplasmic flagella. They produced indole, and did not ferment fructose. They were alpha-glucosidase positive and alpha-galatosidase negative using the APIZYM kit. Using polyclonal antisera raised in rabbits against recognized serotypes, all isolates showed a strong reaction to B. hyodysenteriae antisera E, A and B. Using multilocus enzyme electrophoresis (MLEE) with 15 enzymes and 5 buffer systems, the Korean and non-Korean isolates were divided into 22 electrophoretic types (ETs) and 5 divisions (A, B, C, D and E). Division A corresponded to B. hyodysenteriae, B to B. innocens, C to B. intermedia, D to B. murdochii and E to B. pilosicoli. The 10 Korean isolates of B. hyodysenteriae were relatively diverse, being divided into 9 ETs within MLEE division A. They were all distinct from the non-Korean strains.