Several lines of evidence suggest that plant hormone abscisic acid (ABA) and the activity of alternative respiratory pathway are somehow interrelated. In this paper, we tested how an application of ABA affects the alternative oxidase (AOX) pathway and leaf senescence in Arabidopsis thaliana (L.) Heynh. Different effects of ABA application on the AOX activity were observed under high irradiance (HI) and low irradiance (LI). The expression of AOX1D gene was stimulated, whereas the expression of senescence marker gene WRKY53 was decreased due to ABA treatment. We also noticed that changes of AOX genes AOX1A and AOX1D, as well as AOX regulatory gene ANAC017, were rather inversely correlated with irradiance-dependent changes in AOX activity. The expression of AOX1D and WRKY53 was diminished due to the application of H 2 O 2 under LI. Our results are indicative that in some conditions an exogenous application of ABA may suppress leaf senescence. This action does not go via the induction of AOX activity, despite stimulation of AOX genes.