Powdery mildew is one of the most important fungal diseases of cereal plants. It reduces the yield and the quality of harvested grain. One of the best ways to protect crops against powdery mildew is to introduce effective resistance genes into new cultivars. In this study, diploid species of the genus Triticum were screened to identify potential sources of genetic resistance to powdery mil-dew. Among the analyzed forms, 21 genotypes were identified as fully resistant to all three powdery mildew isolates used. Four of them belong to T. urartu, 12 to T. monococcum, and 4 to T. boeoticum. The tests performed showed that each of the tested species can be a source of genes determining resistance to powdery mildew. The most resistant genotypes were identified among accessions from Lebanon and Syria. Genotypes from Türkiye showed the lowest level of resistance, which indicates that this area is not a region with high pathogen pressure.