The immune and blood coagulation systems have been implicated in the pathophysiology of the geriatric syndrome of frailty, but limited prospective data examining the relationship of clotting/inflammation biomarkers to risk of incident frailty exist.This prospective analysis was derived from a nested case-control study within the Women's Health Initiative. Among women 65 to 79 years free of frailty at enrollment, we randomly selected 900 incident cases from those developing frailty within 3 years; 900 non-frail controls were individually matched on age, ethnicity, and blood collection date. Biomarkers assessed for risk of incident frailty included fibrinogen, factor VIII, D-dimer, C-reactive protein, interleukin-6, and tissue plasminogen activator (t-PA).When examined by quartiles in multivariable adjusted models, higher D-dimer and t-PA levels were each associated with increased risk of frailty (P trend = .04). Relative to the lowest quartile, the odds ratios for frailty compared with the upper quartile were 1.52 (95% confidence interval, 1.05-2.22) for t-PA and 1.57 (95% confidence interval, 1.11-2.22) for D-dimer. For women having high t-PA and high D-dimer compared with women having lower levels of both biomarkers, the odds of frailty was 2.20 (1.29-3.75). There was little evidence for association between coagulation factor VIII, fibrinogen, C-reactive protein, or interleukin-6 levels and incident frailty.This prospective analysis supports the role of markers of fibrin turnover and fibrinolysis as independent predictors of incident frailty in postmenopausal women.