Differences in occurrence of cardiovascular disease between men and women is thought to be attributable to sex differences in arterial stiffness. However, to understand, diagnose and treat CVD, analysis of how and where arterial stiffness affects men and women differently is required. 4D Flow MRI was used to estimate regional and local aortic stiffness in 19 volunteers (age 20-32, 10 men, 9 women). Women had lower regional stiffness, suggesting they experience a reduced afterload on the heart, lowering disease risk. This study provides non-invasive comprehensive stiffness data, previously inaccessible, that may shed light on sex-specific cardiovascular differences.