OBJECTIVE We sought to determine whether assessing D-Dimer might be helpful for the management of acute aortic dissection (AAD). DESIGN Single-center retrospective case-control study. SETTING University Hospital of Strasbourg France. PATIENTS Patients were 94 consecutive patients admitted to our institution with confirmed AAD and in whom D-Dimer test had been performed at presentation. These patients were matched with 94 controls presenting with clinical suspicion of dissection, which was later ruled out. INTERVENTIONS Patient characteristics and clinical course were analyzed. MEASUREMENTS AND MAIN RESULTS Ninety-three (99%) patients with AAD had elevated D-Dimer (>400 ng/mL) with a median D-Dimer value of 8610 ng/mL (interquartile range, 2982-20,000 ng/mL). Receiver operating characteristic curves analysis showed that D-Dimer, but not C-reactive protein, troponin, lactate dehydrogenase, or leukocyte count, was predictive of a diagnosis of AAD, with a sensitivity and specificity of 99% and 34%, respectively. D-Dimer concentration positively correlated with the anatomical extension of the dissection to the different segments of the aorta (R = .47, p < .0001). A positive relationship was observed between D-Dimer and in-hospital mortality rate among patients with AAD (p = .037). On multivariate analysis, the independent predictors of in-hospital mortality were the presence of pericardial effusion (odds ratio, 6.80; confidence interval, 1.87-27.60), D-Dimer >5200 ng/mL (odds ratio, 5.38; confidence interval, 1.27-30.87), and female gender (odds ratio, 4.96; confidence interval, 1.39-19.95). CONCLUSIONS D-Dimers are elevated in patients with AAD and provide valuable diagnostic and prognostic information. In patients with acute chest pain and elevated D-Dimer, a diagnosis of AAD should also be considered. D-Dimer might be a useful complementary tool to the current diagnostic work-up of patients with suspected AAD.