To evaluate whether gender-related differences exist concerning oxidative stress levels in aged patients with coronary artery disease (CAD).Case-control.Clinical and research center.Elderly subjects of both genders with or without CAD.None.Serum hydroperoxides (HP) as index of oxidative stress levels.The HP levels were comparable in aged control subjects of both genders (376 ± 20 arbitrary units [AU] in women, 333 ± 19 AU in men) but significantly increased in CAD (456 ± 15 AU) compared with all control subjects (357 ± 14 AU). Moreover, among CAD patients, the HP levels were higher in women than in men (536 ± 33 AU and 428 ± 15 AU, respectively). Multivariate analysis, in which CAD represented the dependent variable, indicated that dyslipidemia was independently associated with CAD in men (odds ratio [OR] 5.8), whereas HP >50th percentile represented the only strong independent risk factor for CAD in elderly women (OR 8.4).Differences in oxidative stress levels between elderly males and females might provide a biochemical basis for the epidemiologic differences in CAD, which might help to open new opportunities in the management of patients with cardiovascular disease from a gender point of view.