Although the importance of office prehypertension/high normal blood pressure (BP) has been well documented, the significance of ambulatory prehypertension (AmbPreHT) has not been determined. We analyzed markers of target organ damage and hemodynamics in adolescents with AmbPreHT in comparison with hypertensive and normotensive subjects. Out of 304 white patients aged 15.0±2.5 years with office hypertension, 30 children had AmbPreHT and were compared with 66 normotensive healthy children and 92 children with true hypertension (elevated office, ambulatory, and central BP), 22 had ambulatory hypertension (AmbHT), and 70 had severe AmbHT (SevAmbHT). Stroke volume and cardiac output were greater in AmbPreHT compared with patients with normotension but did not differ between AmbPreHT, AmbHT, and SevAmbHT. Similarly, AmbPreHT, AmbHT, and SevAmbHT had similar total peripheral resistance, lower than patients with normotension ( P <0.05). Central systolic BP was higher in patients with AmbPreHT, AmbHT, and SevAmbHT compared with normotensives ( P <0.01). In all 3 groups, the carotid intima-media thickness Z scores were significantly higher than in normotensive ( P <0.001). AmbPreHT and AmbHT patients had higher left ventricular mass index and prevalence of left ventricular hypertrophy compared with normotensive but lower compared with SevAmbHT ( P <0.001). Pulse wave velocity Z scores were increased in patients with AmbPreHT, AmbHT, and SevAmbHT compared with patients with normotension ( P <0.01). Multiple regression analysis showed that body mass index Z score, central systolic BP, and uric acid levels were significant independent predictors of left ventricular mass index. In conclusion, patients with AmbPreHT presented similar cardiovascular adaptations to those observed in patients with hypertensive and may be at risk of developing cardiovascular events.