In situations of food and water deprivation associated with unfavorable environmental conditions, a number of animal species undergo estivation. This state of locomotor inactivity involves a drastic reduction in the metabolic rate, allowing the estivator to survive long periods of adverse situations. However, the arousal from dormancy causes a rapid increase in oxygen consumption, which may elevate the production of oxygen radicals. Thus, it is expected that animals that arouse from estivation suffer a physiological oxidative stress. The reported mechanisms that protect estivators (anurans and gastropods) from the potential dangers of increased oxyradical formation are discussed. This includes the modulation of endogenous antioxidant defenses (enzymes and glutathione) of gastropods during dormancy, preparing them for arousal. A different strategy used for estivating anurans is also discussed.