Chitosan, derivative of chitin is the second most abundant natural polymer and one of the most widely distributed throughout the nature. The numbers of applications of chitosan and their derivatives have been increasing steadily in the last decade. Chitosan has been shown to be a versatile nontoxic material with multiple responses. To date,there is enough evidence indicating that after chitosan application plants can acquire enhanced tolerance to a wide variety of pathogenic microorganisms, unfavorable climatic conditions and improve growth, indicating that the use of natural elicitors such as chitosan might assist in the goal of sustainable agriculture