Aging associates with an increased pro-inflammatory activity that is commonly associated with oxidative tissue damage. One pro-inflammatory molecule that facilitates oxidative stress is leptin, a hormone that regulates metabolism, endocrine and immune functions. To address whether leptin levels correlated with oxidative stress in aging, we performed cross-sectional measurements of circulating plasma leptin in groups of healthy individuals that were divided by age and gender. It was found that leptin levels were comparable between young (N=54) and elderly humans (N=56) in each gender, and women had higher levels than men, irrespectively of age. Interestingly, oxidative stress measured as total glutathione levels correlated positively with elevated leptin levels in elderly women but not in men or in the groups of younger individuals. The data suggest that a gender bias for leptin that is maintained with age can associate with increased propensity to oxidative stress in the elderly