Findings regarding the relation between aortic size and risk factors are heterogeneous. This study aimed to generate new insights from a population-based adult cohort on aortic root dimensions and their association with age, anthropometric measures, and cardiac risk factors and evaluate the incidence of acute aortic events. Participants from the fifth examination round of the Copenhagen City Heart study (aged 20 to 98 years) with applicable echocardiograms and no history of aortic disease or valve surgery were included. Aorta diameter was assessed at the annulus, sinus of Valsalva, sinotubular junction, and the tubular part of the ascending aorta. The study population comprised 1,796 men and 2,316 women; mean age: 56.4 ± 17.0 and 56.9 ± 18.1 years, respectively. Men had larger aortic root diameters than women regardless of height indexing (p <0.01). Age, height, weight, systolic and diastolic blood pressure, mean arterial pressure, pulse pressure, hypertension, diabetes, ischemic heart disease, and smoking were positively correlated with aortic sinus diameter in the crude and gender-adjusted analyses. However, after full adjustment, only height, weight, and diastolic blood pressure remained significantly positively correlated with aortic sinus diameter (p <0.001). For systolic blood pressure and pulse pressure, the correlation was inverse (p <0.001). During follow-up (median 5.4 [quartile 1 to quartile 3 4.5 to 6.3] years), the incidence rate of first-time acute aortic events was 13.6 (confidence interval 4.4 to 42.2) per 100,000 person-years. In conclusion, beyond anthropometric measures, age, and gender, diastolic blood pressure was the only cardiac risk factor that was independently correlated with aortic root dimensions. The number of aortic events during follow-up was low.