A content of reactive oxygen species (ROS) and some parameters of mitochondria functional activity from coleoptiles of winter wheat etiolated acrospires during natural aging and under oxygen stress conditions, induced with treatment of 10 mM hydrogen peroxide (for 4 h), have been studied. It has been shown that the coleoptile aging (as from the 6-th day of growth) is accompanied by a significant decrease of mitochondria intact and the coefficient of a respiration control (RC), an increase of the ROS content in mitochondria and a partial release of the cytochrome c from mitochondria to cytosol. Hydrogen peroxide hastens a cell death in the coleoptiles according to the type of the programmed cell death with mitochondria participation.