Vascular aging is characterized by increased oxidative stress, impaired nitric oxide (NO) bioavailability and enhanced apoptotic cell death. The oxidative stress hypothesis of aging predicts that vascular cells of long-lived species exhibit lower production of reactive oxygen species (ROS) and/or superior resistance to oxidative stress. We tested this hypothesis using two taxonomically related rodents, the white-footed mouse (Peromyscus leucopus) and the house mouse (Mus musculus), that show a more than twofold difference in maximum lifespan potential (MLSP = 8 and 3.5 years, respectively). We compared interspecies differences in endothelial superoxide (O2-) and hydrogen peroxide (H2O2) production, NAD(P)H oxidase activity, mitochondrial ROS generation, expression of pro- and antioxidant enzymes, NO production, and resistance to oxidative stress-induced apoptosis. In aortas of P. leucopus, NAD(P)H oxidase expression and activity, endothelial and H2O2 production, and ROS generation by mitochondria were less than in mouse vessels. In P. leucopus, there was a more abundant expression of catalase, glutathione peroxidase 1 and hemeoxygenase-1, whereas expression of Cu/Zn-SOD and Mn-SOD was similar in both species. NO production and endothelial nitric oxide synthase expression was greater in P. leucopus. In mouse aortas, treatment with oxidized low-density lipoprotein (oxLDL) elicited substantial oxidative stress, endothelial dysfunction and endothelial apoptosis (assessed by TUNEL assay, DNA fragmentation and caspase 3 activity assays). According to our prediction, vessels of P. leucopus were more resistant to the proapoptotic effects of oxidative stressors (oxLDL and H2O2). Primary fibroblasts from P. leucopus also exhibited less H2O2-induced DNA damage (comet assay) than mouse cells. Thus, increased lifespan potential in P. leucopus is associated with a decreased cellular ROS generation and increased oxidative stress resistance, which accords with the prediction of the oxidative stress hypothesis of aging.