The effect of UV-C irradiation on jasmonates, abscisic acid (ABA), polyamines and antioxidant activities was investigated in apple plants (Malus domestica Borkh.). The EC50 values of O2 –-scavenging activity in the UV-C treated leaves were lower than those in the untreated control. In addition, total ascorbic acid and polyphenolic concentrations in the UV-C treated leaves were generally higher than those in the untreated control. Although the endogenous ABA concentrations were not significantly different between the untreated control and UV-C treatment, the endogenous jasmonic acid, putrescine, and spermine concentrations in the UV-C treated plants were higher than those in the untreated control. However, the application of PDJ before UV treatment inhibited the rise of endogenous jasmonate and putrescine concentrations. The increase of ascorbic acid was also inhibited by PDJ application before UV treatment. These facts suggest that the increase of jasmonates and polyamines may be associated with UV-C stimulation, and UV-C irradiation may be effective for increasing antioxidant activity in apple leaves. KeywordsJasmonates–Polyamines– Malus domestica Borkh.–Ultraviolet irradiation