the antibiotic and antixenotic resistance of six commonly produced potato cultivars in iran including aozonia, agria, cosima, cosmos, kondor and savalan to the green peach aphid, myzus persicae sulzer, were investigated under laboratory conditions at 20 ± 2oc, 65 ± 5% rh and 16:8h (l:d) in 2009. antibiosis experiments showed significant differences in the developmental time, nymphal survivorship, fecundity, adult longevity of the green peach aphid among the potato cultivars. intrinsic rate of natural increase (rm) for apterous aphids varied significantly with the potato cultivars on which the aphids were reared. this value ranged from 0.225 to 0.293 females/female/day, which was lowest on cosmos and highest on aozonia. additionally, the estimated net reproductive rate (r0) and finite rate of increase (λ) for apterous aphids were the lowest on cosmos. for the antixenosis experiment, no significant difference was found in aphid's preference to the potato cultivars. however, aozonia was preferred more than the other five cultivars by the apterous aphids. therefore, our results demonstrated that among the investigated cultivars the cosmos cultivar is moderately resistant to the green peach aphid.