Background: Little information is available regarding the relationship between ascending aortic length and acute aortic events. We aim to evaluate whether patients with acute type A aortic dissection (ATAAD) exhibit differential aortic measurements compared to control patients. Methods: Data were collected on patients with ATAAD and control patients who received imaging for unrelated conditions. Propensity score matching was conducted using age, sex, race, body surface area, and hypertension in the logistic model. After matching, 67 patients remained in each group. Aortic morphometry was assessed via computed tomographic angiography. Ascending aortic length was defined as the centerline distance between the sinotubular junction (STJ) and the origin of the brachiocephalic trunk. Results: The mean ascending aortic length was 76.9 ± 15.7 mm (range 36.8 to 115.0 mm) for patients with ATAAD and was 62.0 ± 10.7 mm (range 34.0 to 87.8 mm) for control patients, which was a significant difference (t=-6.4, P<0.001). ATAAD patients had greater diameter at STJ (median: 41.6 vs 30.2 mm, z=7.5, P<0.001) and diameter at PAB (median: 42.3 vs 32.2 mm, z=6.8, P<0.001) compared with controls. A maximum ascending aortic diameter >5.5 cm (at either the PAB or STJ) was present in 12 of 67 cases (18%) and 0 of 67 controls (P<0.001). Conclusions: Ascending aortic length is significantly greater in patients who experienced ATAAD compared to matched controls. Elongation of the aorta may play a role in the pathogenesis of ATAAD, and assessment of ascending aortic length may be valuable as a predictive marker for aortic events.