The influence of the salicylic and succinic acids on the cytophysiological reactions of the plants and cellular structures of the fungus were investigated using the model of common wheat Triticum aestivum L. infected by brown rust. The experiments were performed on seedlings of the isogenic line of var. Thatcher with resistant gene Lr19. The salicylic and succinic acids accelerated and enhanced to a different extent the generation of active oxygen species and synthesis of callose and phenylpropanoids by the plant cells contacting with cellular structures of avirulent and virulent fungal clones.