A four-years field study was conducted in El-Gemmeiza Agricultural Research Station to assess the susceptibility of 10 flax genotypes to powdery mildew and to determine the effect of the disease on yield and yield components. Disease incidence was used to evaluate susceptibility of the genotypes to the disease. None of the tested genotypes showed satisfactory levels of resistance to the disease. However, cultivar Giza 7, line 366/2/1/2 and line 5 were the least susceptible genotypes. These genotypes showed superiority in some agronomic traits compared to the other genotypes. Many significant correlations were observed among agronomic traits as well as technological traits each year. On the other hand, very few significant correlations were observed between disease intensity variables (DI and DS) and agronomic or technological traits.