['Previous reports indicate that D-dimer testing (DT) for acute aortic dissection (AAD) has a sensitivity of 100%, but each study comprised less than 30 patients. The aim of this study was to evaluate the positive rate and factors related to the results of DT for AAD in a larger population.', 'DT (cutoff; upper normal limit) was performed for 113 consecutive AAD patients within 24 h of symptom onset. In total, 104 (92%) patients exhibited positive DT. The positive rate of DT showed a low tendency in patients aged less than 70 years and for a time interval from symptom onset to admission within 120 min, and there were significant differences between those with and without a thrombosed false lumen (TFL) (86.4% (n=59) vs 98.1% (n=54), p=0.033), complete TFL (excluding patients with ulcer-like projection (ULP) from those with a TFL) (81.1% (n=37) vs 97.4% (n=76), p=0.005) and length score (1 (n=28); 78.6%, 2 (n=40); 95.0%, 3 (n=45); 97.8%, p=0.005). Multivariate analysis demonstrated age (odds ratio =1.164, p=0.013), complete TFL (0.048, 0.030) and length score (6.271, 0.033) as independent factors.'] Are young adult patients with short dissection length and thrombosed false lumen without ulcer-like projections liable to have false-negative results of D-dimer testing for acute aortic dissection based on a study of 113 cases?