Bread and durum wheats are among the most important cultivated crop plants worldwide. Powdery mildew caused by Blumeria graminis f. sp. tritici is one of the most destructive foliar diseases of wheat, affecting yield and end-use quality, especially in areas with a cool or maritime climate. Breeding for resistance using diversified disease resistance genes is the most promising approach to prevent outbreaks of powdery mildew. To date, more than 60 genes/alleles have been identified and mapped on the wheat chromosomes, and many of these genes have been extensively used in breeding. Very few have been cloned, but most of them have been tagged with molecular markers, especially microsatellites, useful for marker-assisted selection, allowing selection for resistance in the absence of the pathogen. The details about most of the resistance genes mapped on the wheat genome, the source of resistance and molecular markers tightly associated to them have been reviewed.