The authors hypothesized that personality disorders characterized by interpersonal hypersensitivity would be associated with an elevated concentration of 8-hydroxy-2'-deoxyguanosine (8-OH-DG), the oxidized form of guanine, and a biomarker of oxidative stress burden. One hundred ninety-five male and female adults underwent semistructured diagnostic interviews, completed questionnaire measures of social cognition and emotional attribution, and had blood drawn for determination of plasma 8-OH-DG. A hierarchical linear regression model revealed that narcissistic and borderline personality disorders predicted 8-OH-DG level independently of the effects of age, gender, recent alcohol and cigarette use, current major depression, and posttraumatic stress disorder. In all subjects, 8-OH-DG level was also correlated with the number of borderline personality disorder symptoms present. Narcissistic and borderline personality disorders predicted oxidative stress burden independently of potentially confounding factors.