The effects of exogenous jasmonic acid (JA) on antioxidant enzymes in four week old leaves of wild type Arabidopsis thaliana L. (Columbia 0) and jin1 (jasmonate insensitive 1) mutant plants with defective jasmonate signaling were investigated under normal conditions and under salt stress (200 mM NaCl, 24 h). The wild type plants responded to JA by an increase in the activities of Cu/Zn superoxide dismutase, catalase, and guaiacol peroxidase, while there was no change in the case of the mutant plants. In response to the salt stress of both the wild type and mutant genotypes, the activities of superoxide dismutase, catalase, and guaiacol per oxidase were unchanged, decreased, and increased, respectively. The JA treated wild type plants showed the highest activity of all three enzymes as compared with the mutant plants. Salinity caused a decrease in chloro phyll content in the wild type and jin1 plants. Preliminary JA treatment of the Col 0 plants resulted in a normal content of photosynthetic pigments after the salt stress, while the positive JA effect was insignificant in the jin1 mutants. It was concluded that the MYC2/JIN1 protein is involved in the JA signal transduction and plant adaptation to salt stress.