twenty advanced watermelon breeding lines, derived from the cross between cv. crimson sweet (susceptible) and pi 595201 (resistant to wmv and prsv-w), were screened for resistance to both potyviruses. the twenty lines, among with crimson sweet and pi 595201, were inoculated with either wmv or prsv-w, in two different greenhouse trials. plants were evaluated for symptoms 35 and 49 days after the first inoculation (dai), using a scale from 1 (no symptoms) to 5 (severe mosaic and foliar distortion). evaluations at 35 dai indicated that lines 1, 2 and 20 had good levels of resistance to both wmv and prsv-w, with ratings of 1,95, 1,80 and 2,25 for wmv, and of 2,50, 2,30 and 2,50 for prsv-w, respectively. lines 5, 7 and 13 were resistant to wmv only, whereas lines 3, 10 and 18 were resistant to prsv-w only. the reaction of the lines 49 dai remained essentially unchanged. the existence of lines with resistance to wmv only and to prsv-w only, along with lines with resistance to both viruses, indicates that resistance to wmv and prsv-w are under control of different genes.