Recent genetic analyses of longevity in animals have revealed that long-lived strains are more tolerant to environmental stresses. To investigate whether extended longevity in Arabidopsis also correlates with an increase in stress tolerance, the response was tested of 11 late-flowering mutants to the superoxide radical-generating herbicide paraquat. A tight correlation between flowering time and paraquat tolerance was found when plants were exposed to low doses of herbicide. Furthermore, the mutant gigantea (gi-3) with the longest delay in flowering time had a high tolerance level to paraquat-induced oxidative stress. All the tested gi alleles had an increased tolerance to paraquat toxicity compared to wild-type, although the actual levels of tolerance differed. In addition, the gi-3 mutant was more tolerant to hydrogen peroxide. These results suggest that the link between longevity and oxidative stress resistance in plants is similar to that found in animals, implying that this phenomenon may be general for all aerobic organisms.