In many terrestrial ecosystems elevated atmospheric carbon dioxide (CO₂) may reduce plant quality and change plant-herbivore interactions. The objective of this study was to evaluate the effects of elevated CO₂ (600 ppm vs. 350 ppm) on white clover (Trifolium repens L.) and to examine the feeding response and growth of juveniles of the helicid land snail Arianta arbustorum (L.). Leaves of T. repens grown at elevated atmospheric CO₂ had a lower nitrogen concentration and a lower specific leaf area than leaves grown under ambient CO₂ conditions. However, elevated CO₂ had no effect on leaf carbon concentration. Juvenile snails fed on either diet consumed about the same amount of leaf biomass. The lower leaf nitrogen concentration at elevated CO₂ resulted in a reduced nitrogen uptake. As a consequence, juvenile A. arbustorum, fed on T. repens grown under elevated CO₂, tended to grow more slowly than snails fed on T. repens leaves produced under ambient CO₂. This indicates that rising atmospheric CO₂ can indirectly affect the life cycle of terrestrial gastropods.