This study was conducted to study left ventricular hypertrophy (LVH), diastolic dysfunction, pulse pressure (PP), and plasma endothelin (ET)-1 level in amateur marathon runners with an exaggerated blood pressure response (EBPR) to exercise. The study participants included normotensive marathon runners (NM, n = 15), EBPR marathon runners (EBPR, n = 17), normotensive sedentary individuals (CON, n = 13), and hypertensive patients (HTN, n = 14). An integrated M-mode/2-dimensional echocardiographic analysis was performed. Plasma ET-1 levels at resting were measured using a commercial ELISA kit. LV wall thickness and end-diastolic dimensions as well as LV mass index (LVMI) were higher in EBPR than in CON. There were no differences in systolic function among the groups. Analysis of diastolic function, such as lower Em and higher E/Em ratio on TDI, showed a worse relaxation pattern in EBPR. Despite LVH, NM subjects showed no abnormality of LV diastolic dysfunction. HTN subjects in the early stage of their disease showed a slightly modified LV structural and diastolic function, but there was no statistical difference compared with CON. The E/Em ratio was significantly correlated with PP and LVMI. LVMI was significantly correlated with PP. There was a significant difference in plasma ET-1 concentration between marathon runners and hypertensive subjects. We demonstrated that marathon runners with EBPR showed an increase in LVMI and diastolic dysfunction more than HTN subjects in the early stage. PP was significantly related to these two variables. Caution should be exercised when connecting LVH and diastolic dysfunction with plasma ET-1 concentration in all marathon runners.