Oxidative stress has been advanced as one of the major causes of damage to DNA and other macromolecules. Although physical exercise may also increase oxidative stress, an important role has been recognized for regular exercise in improving the overall functionality of the body, as indicated by an increase in maximal aerobic uptake ((V)O2max), and in resistance to cell damage. The aims of this study were 1) to evaluate the association between DNA damage in human lymphocytes and age and 2) to evaluate the association between DNA damage in human lymphocytes and ((V)O2max. The sample was composed of 36 healthy and nonsmoking males, aged from 20 to 84 years. ((V)O2max was evaluated through the Bruce protocol with direct measurement of oxygen consumption. The comet assay was used to evaluate the DNA damage, strand breaks and formamidopyrimidine DNA glycosylase (FPG)-sensitive sites. We found a positive correlation of age with DNA strand breaks but not with FPG-sensitive sites. ((V)O2max was significantly inversely related with DNA strand breaks, but this relation disappeared when adjusted for age. A significantly positive relation between ((V)O2max and FPG-sensitive sites was verified. In conclusion, our results showed that younger subjects have lower DNA strand breaks and higher (V)O2max compared with older subjects and FPG-sensitive sites are positively related with ((V)O2max, probably as transient damage due to the acute effects of daily physical activity.