Acute aortic dissection (AAD) is uncommon, and associated with high morbidity and mortality rates. Positive or negative likelihood ratios of clinical parameters, ECG and chest x-ray do not allow to rule in or rule out AAD. Angio-CT, transoesophageal echocardiography, and MRI are validated tools for AAD diagnosis, although they are invasive and associated with significant complications. In several studies, D-dimer level within the normal range appears to have a negative predictive value that is low enough to rule out AAD. However, flaws of study design, heterogeneity of D-dimer tests and of their cut-offs (from 100 to 900 microg/l), and the absence of a validated workup strategy are strong arguments against the current use of D-dimer as a unique test to rule out AAD in clinical practice.