Recently, malaria re-emerged in the Republic of Korea (ROK), but there have been only a few reports on malaria seroprevalence. For the epidemiological study in children, a total of 1,176 serum samples were obtained from children and adolescent inhabitants from the three different regions, Pajoo, the Guro district in the western part of Seoul (Guro), and Ansan, from June to September 2002, when the transmission rate was high. Anti-circumsporozoite protein (CSP) antibody levels were assessed in samples using an indirect enzyme-linked immunosorbent assay (ELISA) method. Among the three regions, the highest IgG seroreactivity against the CSP antigen of Plasmodium vivax was found in the children from Pajoo (8.0%), followed by the children from Guro (3.2%), and those in Ansan (0.02%) had the lowest seroreactivity. In Pajoo, the profile of antibody response showed the highest in age 9, but decreased with age towards 12 years old. We found significant correlation between the seroprevalence and annual incidence in the investigated areas, suggesting that the area-related patterns reflected the differences of inoculation rates in children.