Artificial crossing experiments involving 3 Abies species native to Korean peninsula and 5 other representatives of Abies revealed a high hybridological affinity between Abies koreana and A. nephrolepis. Both these species are reproductively isolated from A. holophylla. All the three Korean species were found to exhibit incompatible relationships with the North American species A. concolor. The species A. holophylla and A. koreana differ also in their abilities to intercross with the Mediterranean firs. The former has been successfully crossed with A. nordmanniana, A. alba and A. cilicica exhibiting 19.1–55.3% crossability, whereas the latter produced filled seeds only with A. nordmanniana reaching 46.4% crossability. A considerable differentiation is postulated to exist between the pair of species A. koreana and A. nephrolepis on the one side and A. holophylla on the other side.