Objectives: To investigate whether adherence to a Mediterranean dietary pattern during adolescence and early adulthood affects arterial stiffness in adulthood, and the extent to which any such association may be attributed to a beneficial impact of this diet on cardiovascular disease risk factors such as blood pressure, central fatness and dyslipidaemia. Setting: The Amsterdam Growth and Health Longitudinal Study. Design and subjects: We compared longitudinal levels of adherence to a Mediterranean dietary pattern (aMED score with range 0-9) during adolescence and adulthood (two to eight repeated measures obtained between the ages of 13 and 36) between individuals with different levels of arterial stiffness in adulthood. The study population included 373 (196 women) apparently healthy adults in whom properties of the carotid, brachial and femoral arteries were assessed using ultrasonography at 36 years of age. Results: After adjustments for potential confounders, individuals with stiffer carotid arteries (defined on the basis of the most adverse tertile of, for instance, the distensibility coefficient) had lower aMED scores (-0.32, 95% CI -0.60; -0.06) and were less likely to have adhered to this dietary pattern (aMED score ≥5, odds ratio 0.69, 95% CI 0.50; -0.94) during the preceding 24 years compared with those with less stiff arteries. Differences in aMED scores were already present in adolescence and were only in part explained by the favourable associations between the Mediterranean dietary pattern and other cardiovascular disease risk factors (up to 26%), particularly mean blood pressure (up to 19%). Conclusions: Promoting the Mediterranean diet in adolescence and early adulthood may constitute an important means of preventing arterial stiffness in adulthood. © 2012 The Association for the Publication of the Journal of Internal Medicine.