Apical membrane antigen-1 is a candidate vaccine component for malaria. In the present study, we investigated the polymorphism of the Plasmodium vivax apical membrane antigen-1 gene ( PvAMA-1) in 30 Korean isolates. The polymorphic region of the PvAMA-1 gene, corresponding to nucleotides 324-735 (aa 108-245), was amplified using polymerase chain reaction followed by cloning and sequencing. Two genotypes ( SKA and SKG) were identified on the basis of amino acid substitution. These were identical to those of the Chinese isolates. The Korean isolates showed sequence variation at six positions on the basis of the sequence of the Sal1 strain. Of these, variation at position 189 (Glu/Lys) was found only in SKA. These two genotypes were related to the genotype of the circumsporozoite and Duffy binding protein of the Korean isolate. These findings suggest that two genotypes of P. vivax coexist in the endemic area and that the re-emerging parasite in Korea may be related to or have originated in East Asia.