By using allele-specific polymerase chain reaction, self-incompatibility (S)-genotypes of the Korean apple cultivars were analyzed to identify their self-incompatibility relationship. S-genotypes of the cultivars were determined as 'Hongro', 'Saenara', 'Hongso', and 'Hongan', S (1) S (3) ; 'Picnic', S (1) S (5) ; 'Gamhong', 'Manbok', 'Hwarang', 'Yeohong', 'Danhong', and 'Hwayoung', S (1) S (9) ; 'Seokwang', S (3) S (5) ; 'Honggeum' and 'Greenball', S (3) S (7) ; 'Sunhong', 'Seohong', 'Chukwang', and 'Hwahong', S (3) S (9) ; and 'Summer Dream', S (7) S (9) . These results will help to select compatible pollinizers and design apple orchards.