Canine parvovirus type-2 (CPV-2) is one of the major diarrhea-causing agents, inducing acute hemorrhagic gastroenteritis in puppies. In this study, we conducted a seroepidemiological survey of CPV-2a in stray dogs in South Korea. In total, 405 canine sera, collected between 2006 and 2007, were screened for the presence of antibodies against CPV-2a using a hemagglutination inhibition (HI) assay. The positive rate in stray dogs tested for CPV-2a was 93.8%. The regional CPV-2a prevalence was 100% (8/8) in Jeju, 95.1% (232/244) in Gyeonggi, 94.7% (36/38) in Jeonra, 92.9% (13/14) in Gangwon, 92.7% (38/41) in Chungcheong, and 88.3% (53/60) in Gyeungsang province. No significant difference in the seropositive rate was found between male (93.6%) and female (94.0%) dogs. Analysis of the distribution of HI titer against CPV-2a according to the age of the stray dogs showed a linear increase in seroprevalence with age, although the association with age was not statistically significant. The incidence of stray dogs showing an HI antibody titer above 1:5120 was estimated to be 26.2%. Thus, the presence of high HI antibody against CPV-2a may indicate circulation of CPV-2a in stray dogs.