In the second half of vegetation period of plants growing in severe drought conditions the highest activity of photosynthesis and photorespiration was recorded in last mature leaves of Aligote variety shoots and in the middle part of shoots of the adherents of Cardinal variety in relation to the principals. We consider that the higher activity of these leaves in this period contribute to the accumulation in grapes the saccharides as well as the reserve substances necessary in plant preparation for wintering: and the photorespiration – to the protection of photosynthetic apparatus from destructive exposure of light in case of CO2 insufficiency (during drought) in leaves, and also to the formation of very important intermediary compounds (glycine, serine).