The seedlins of growing flax cultivars and promising strains exhibited various reaction of seedling damping–off. Fusarium spp.;Rhizoctoniasolani ; Pythium spp.; Macrophomina phaseolina and Sclerotium rolfsii were isolated from affected seedlings and shown to be pathogenic to flax under specific controlled conditions. A wide range of resistance among and within varieties resulted from the difference among varieties to the same isolates and the different reaction of a single variety to many isolates. Isolates of Rhizoctonia solani and Macrophomina phaseolina were the primary agents in pre-emergence damping-off and were associated with sever necrosis of roots and/or hypocotyls. Macrophomina and Fusarium induced severe post-emergence, and induced severe root necrosis on surviving plants. All of the three pathogens considered important components of the flax seedling damping–off diseases.