Abstract: The genetic relationship of 13 oriental melon (Cucumis melo L.) was determined using random amplified polymorphic DNA (RAPD) analysis with 12 dodecamer oligonucleotide primers. Representative cultivars could be divided into two major groups at 0.756 similarity value. One group included 7 makuwa melons namely, ‘ Nara-1-gou ’, ‘ Tiger-melon ’, ‘ Kinpyou ’, ‘ Kiku-melon ’, ‘ Nashi-makuwa ’, ‘ Shouwa-melon ’ and 4 conomon melons namely, ‘ Numame-shirouri ’, ‘ Katsura-ohoshirouri ’, ‘ Tokyo-ohoshirouri ’, ‘ Kuromonao-ohoshirouri ’. The other major group included 2 makuwa cultivars namely ‘ Ginsen ’ and ‘ Wasegin ’. The RAPD showed that conomon melon belonged to same species as makuwa melon. It seemed that, makuwa melon is an allogamous plant which hybridizes easily with table-melons and conomon melon and it might have hybridized with conomon melon in the distant past.