Twenty isolates resistant to seven quinolones were isolated from major rivers in Korea. All isolates had three mutations, Ser83→Leu and Asp87→Asn in GyrA and Ser80→Ile or Ser80→Arg in ParC and three isolates had an additional mutation Glu84→Gly or Glu84→Val in ParC. In addition, a clonal spread was not found in these isolates.