Apple seedlings (Malus domestica Borkh.) were grown under ambient (370), 700, and 1400 μmol·mol-1 CO2 regimes and artificially damaged by removal of leaf area (0%, 15%, and 30%). Increased CO2 concentration had a highly significant effect on the concentrations of sucrose, sorbitol and phloridzin, however there were no significant interactions between CO2 concentration and leaf damage. As CO2 concentration increased there was an increase in levels of sucrose and phloridzin, whereas sorbitol concentration decreased. These findings are discussed in relation to the carbon nutrient balance hypothesis as well as other hypotheses regarding the production of plant primary and secondary compounds in response to elevated levels of CO2 and mechanical damage and/or herbivory.