In order to elucidate the intergeneric relationshiops within Korean Oleaceae including the endemic Abeliophyllum distichum, 19 species and 9 varieties of 9 genera were investigated. A cladistic analysis based on 18 characters revealed close relationships among (1) Osmanthus, Chiononthus, Fraxinus, (2) Abeliophyllum, fontanesia, Forsythia, and (3) Ligustrum, Syringa, and well accorded with the pollen morphological result. Jasminum was connected to the branch of Ligustrum possibly owing to a sampling error. A hypothesis on the origin of Abeliophyllum was drawn that it originated from Fontanesi or less probably from the common ancestor of Fontanesia and Forsythia.