We report on the cloning of resistance-gene homologues from the melon genome that belong to two gene families: the Pto-receptor-kinase family and the leucine-rich repeat R-genes family. The melon homologues have been cloned by PCR using conserved sequence motifs. We are currently trying to place them on a linkage map developed in our laboratory and to obtain full-length Pto-like clones. A preliminary map, derived from an F2 population of the cross between PI 414723 and cv. Top Mark, is presented. It includes 107 points, consisting of RAPD, ISSR, SSR, and RFLP markers and the aphid-resistance trait. Many RFLPs represent sequence-characterized cDNAs and genomic fragments from Cucumis melo and Cucumis sativus. The SSR markers have been used to identify our linkage groups with those of other, more complete melon maps.