During the last 3 years, foot-and-mouth disease virus serotype O, named PanAsia, caused two outbreaks in the Republic of Korea. To determine if there was an obvious genetic relationship between the virus isolated in 2002 (O/SKR/2002) and the O/SKR/2000, and to further analyze the epidemiological relationships between the PanAsia viruses and the viruses identified in Korea, the complete nucleotide sequence of the O/SKR/2002 and the O/SKR/2000 were determined by automatic cycling sequencing and primer walking. The nucleotides and the deduced amino acid (aa) sequences of the strains identified in Korea were compared with each other and also those enrolled in the GenBank database. In comparison and analysis of the viruses identified in Korea, any deletions or insertions in the specific fragment gene of both the O/SKR/2002 and O/SKR/2000 were not identified. However, comparison of the aa sequence of the identified virus in 2002 from pigs with those of other PanAsia strains revealed significant substitutions of 4 aa in the VPI region and 8 aa in the 3A region. In phylogenetic analysis based on the translated region, the identified virus in 2002 appeared to be the divergence of approximately 1% degree with other PanAsia viruses. Also, animal experiments indicated that O/SKR/2000 is not host-restricted and develop the clinical signs in the main susceptible livestock species (cattle and pigs). However, O/SKR/2002 did not develop the clinical signs in cattle and showed severe clinical signs only in pigs. These analytic data suggest that 2002 outbreaks in Korea is not re-occurred but re-introduced from nowhere.