The aim of the present investigation was to check the ability of experimentally farmed Helix aspersa (O. F. Müll.), raised in conditions enabling rapid growth and successful reproduction, to modulate their antioxidant defence system during enforced aestivation. The aestivation induced increase in activity of total and selenium-dependent peroxidase in the kidney and foot but did not evoke increase in activity of catalase, glutathione transferase and concentration of reduced glutathione. Moreover, the aestivation did not induce lipid and protein peroxidation, estimated as concentrations of thiobarbituric acid and carbonyl protein groups, respectively. H. aspersa farmed under favourable or natural conditions are able to modulate their antioxidant defence system in response to oxidative stress following transition from the experimental aestivation to active state.