Ethylene and hydrogen peroxide are involved in the modulation of stress responses in plants, but their interrelation is not well understood. This work was designed to find differences between the actions of ethylene and H 2 O 2 on antioxidants and senescence markers. Leaves of Nicotiana tabacum were sprayed with H 2 O 2 or with ethephon (precursor of ethylene). To find the possible modulation of responses to acute abiotic stress, ethephon- and H 2 O 2 -sprayed leaves were further subjected to high irradiance (HL). The application of H 2 O 2 strongly stimulated ethylene synthesis (ACC). Ethylene and H 2 O 2 , as single factors, stimulated the trolox equivalent antioxidant capacity (TEAC) and the activity of catalase (CAT), in contrast to HL alone (stimulation of nonspecific peroxidases and the total glutathione pool). However, after combined treatments (ethylene+HL and H 2 O 2 +HL), the stimulatory action of H 2 O 2 was related to TEAC and CAT activity, while the application of ethylene stimulated the total glutathione pool. Hydrogen peroxide enhanced the expression of the three CAT genes (Cat1, Cat2 and Cat3), in contrast to ethylene (Cat2 and Cat3) and HL (Cat1). In regard to the markers of senescence and pathogenesis the most pronounced difference between the actions of ethylene and H 2 O 2 , as single factors, was related to NPR1, whereas when leaf spraying was combined with HL, differences were found at WRKY53 and PR1a. HL reversed the stimulatory effects of H 2 O 2 /ethylene-driven enhancements of the expression of several genes (Cat1, Cat2, NPR1, WRKY53). These results show that multiple stressors, as usually encountered by plants in nature, may largely change those expression patterns of genes determined in a single factor analysis. Moreover, the actions of HL (often considered the internal H 2 O 2 trigger) and of exogenous H 2 O 2 on gene expression are clearly different.