Early onset hypertension confers increased risk for cardiovascular mortality in the community. Whether early onset hypertension also promotes the development of target end-organ damage (TOD), even by midlife, has remained unknown. We studied 2680 middle-aged CARDIA study (Coronary Artery Risk Development in Young Adults) Study participants (mean age 50±4 years, 57% women) who underwent up to 8 serial blood pressure measurements between 1985 and 2011 (age range at baseline 18–30 years) in addition to assessments of echocardiographic left ventricular hypertrophy, coronary calcification, albuminuria, and diastolic dysfunction in 2010 to 2011. Age of hypertension onset was defined as the age at first of 2 consecutively attended examinations with blood pressure ≥140/90 mm Hg or use of antihypertensive medication. Participants were divided in groups by hypertension onset age (<35 years, 35–44 years, ≥45 years, or no hypertension). While adjusting for TOD risk factors, including systolic blood pressure, we used logistic regression to calculate odds ratios for cases (participants with TOD) versus controls (participants without TOD) to examine the relation of hypertension onset age and hypertensive TOD. Compared with normotensive individuals, hypertension onset at age <35 years was related to odds ratios of 2.29 (95% CI, 1.36–3.86), 2.94 (95% CI, 1.57–5.49), 1.12 (95% CI, 0.55–2.29), and 2.06 (95% CI, 1.04–4.05) for left ventricular hypertrophy, coronary calcification, albuminuria, and diastolic dysfunction, respectively. In contrast, hypertension onset at age ≥45 years was not related to increased odds of TOD. Our findings emphasize the importance of assessing age of hypertension onset in hypertensive patients to identify high-risk individuals for preventing hypertensive complications.