Peach powdery mildew (podosphaera pannosa) is one of the most economically destructive diseases of grapevines all over the world including Iran. In order to evaluate the 25 genotypes of peaches reaction against powdery mildew an experiment was conducted in Randomized Complete Block Design with three replications during 2014-2015 in Agriculture and Natural Resources Research Station in Meshginshahr. The research was conducted in two conditions of natural infection and artificial inoculation. Genotypes included Robin, Red heven, Early red, Spring crest,Vesevio, Red top, J.H. Hale, Shasta, Early glo, Amesdn, Loring, Spring time, Velvet, Sudanell, Sundance, Anjiri, Haj kazemi, Paeizeh, Elberta, Baby gold7, Dixi red, Red skin, Sabz-e-Mashhad, Sun crest and July Elberta. The evaluate on different genotypes of peaches reaction to powdery mildew was don using Ivascu and Buciumanu (2006) as follow: 0: Immune, 1: Very resistant 2: Resistant 3: Medium resistant 4: Sensitive and 5: Very sensitive. The results of two year evaluation showed that there were significant differences between the degrees of resistance against the studied disease among the treatments. Comparison of means showed that the genotypes J.H. Hale, Anjiri, Loring, Red top, Red heven and Early glo very resistant; Vesevio, Elberta, Spring crest, Velvet, Shasta, Early red, Red skin and July Elberta in resistant; Baby gold7, Sundance, Amesdn, Haj kazemi, Spring time, Dixi red and Robin in medium resistant; Sun crest and Sudanell in sensitive and Sabz-e-Mashhad and Paeizeh were very sensitive genotypes.