Purpose: The aim of this study was to explore the full spectrum of aortic root (AR) diameters by two-dimensional transthoracic color-Doppler echocardiography (TTE) in a large cohort of healthy subjects. Methods: From June 2007 to December 2013, 1043 healthy volunteers [mean age 44.7±15.9 years, range 16 to 92; 503 (48%) men] underwent comprehensive TTE. Two–dimensional measurements of the aortic root were made at enddiastoleenddiastole in parasternal long-axis views at 4 levels: (1) annulus; (2) sinuses of Valsalva; (3) supra-aortic ridge; and (4) proximal ascending aorta. Results: The absolute aortic diameters were significantly greater in men than in women at all levels while BSA indexed aortic diameters were greater in women. (Table 1) There was a straight correlation between the aortic diameters (absolute and indexed values) with age in both genders (p=0.0001). Table 1. Gender differences in aortic diameters Aortic Root Absolute Values (mm) Indexed Values (mm/m2) Men Women p Men Women p Annulus mean 21.0±2.2 18.7±1.6 0.0001 10.9±1.3 11.2±1.1 0.0001 25th 19.2 18.0 10.0 10.5 75th 22.0 20.0 11.7 11.9 Sinuses of Valsalva mean 31.8±3.7 28.5±3.0 0.0001 16.5±2.2 17.1±2.1 0.0001 25th 29.0 26.0 15.1 15.7 75th 34.0 31.0 17.8 18.3 Sinotubular junction mean 26.9±3.7 24.4±2.9 0.0001 14.0±2.1 14.6±1.9 0.0001 25th 24.0 22.0 12.5 13.4 75th 29.0 26.0 15.2 15.8 Proximal acending aorta mean 29.1±4.3 27.4±3.4 0.0001 15.1±2.5 16.5±2.1 0.0001 25th 26.0 25.0 13.5 15.1 75th 32.0 30.0 16.6 17.8 Data are presented as mean ± standard deviation, 25 and 75 percentile. p values indicate the differences among genders. Conclusions: We provide the full range of AR diameters by TTE. Knowledge of upper physiologic limits of aortic dimensions is mandatory in order to detect aorta dilatation and planning appropriate follow-up and therapeutic interventions