Caloric restriction (CR) has been associated with healthbenefits and these effects have been attributed, in part, tomodulation of oxidative status by CR; however, data are stillcontroversial. Here, we investigate the effects of seventeenweeks of chronic CR on parameters of oxidative damage/modification of proteins and on antioxidant enzyme activitiesin cardiac and kidney tissues. Our results demonstrate that CRinduced an increase in protein carbonylation in the heartwithout changing the content of sulfhydryl groups or theactivities of superoxide dismutase and catalase (CAT).Moreover, CR caused an increase in CAT activity in kidney,without changing other parameters. Protein carbonylation hasbeen associated with oxidative damage and functionalimpairment; however, we cannot exclude the possibility that,under our conditions, this alteration indicates a differentfunctional meaning in the heart tissue. In addition, wereinforce the idea that CR can increase CAT activity in thekidney.