Abstract--Cigarette smoking is an important modifiable cardiovascular risk factor and pathophysiological mechanisms may include a stiff vascular tree. Although smokers have stiffer arteries, whether smoking cessation is associated with reduced arterial stiffness is not known. We compared never-treated patients with essential hypertension (n=554) aged 18 to 80 years (56% females) classified as current smokers (n=150), ex-smokers (n=136), and nonsmokers (n=268). Ex-smokers were categorized into <1 year, >1 and <10 years, and >10 years of smoking cessation. Measurements included aortic stiffness, assessed as pulse wave velocity (Complior), wave reflection (augmentation index [AIx]), and transit time (T_R) (Sphygmocor). Current and ex-smokers had significantly higher pulse wave velocity and AIx compared with nonsmokers (pulse wave velocity for current smokers: 10.7±0.2; ex-smokers: 10.6±0.2; nonsmokers: 9.9±0.1 m/s; P<0.001; AIx for current smokers: 31±1; ex-smokers: 30±1; nonsmokers: 27±0.8%; P<0.05), whereas T_R was lower in current and ex-smokers compared with nonsmokers (T_R for current smokers: 131±1.0; ex-smokers: 135±1; nonsmokers: 137±0.8 m/s; P<0.0001). There was a significant linear relationship between smoking status and pulse wave velocity (P<0.001), AIx (P<0.001), and T_R (P<0.001), even after adjusting for age, sex, mean arterial pressure, heart rate, and body mass index. In ex-smokers, duration of smoking cessation had a significant linear relationship with improvement in pulse wave velocity (P<0.001), AIx (P<0.001), and T_R (P<0.001), with arterial stiffness parameters returning to nonsignificant levels after a decade of smoking cessation.