We hypothesized that aortic forward pressure wave amplitude, which is determined by characteristic impedance (Zc) and peak flow in the proximal aorta, contributes to increased left ventricular (LV) mass observed in overweight (OW) adolescents. Aortic pulsatile hemodynamics were measured non-invasively in sixty healthy adolescents (age 14–19 yrs; 42% male) by sequential recordings of pulse waveforms via tonometry, brachial BP, and pulsed Doppler and diameter of aortic outflow tract using 2D echocardiography. LV structure and function was assessed by 2D echo. OW adolescents (n=23; age 16.0 ± 0.3 yrs; BMI ≥85^th percentile) had higher LV mass index (LVMI), brachial and carotid systolic BP and PP (all P<0.05), but not mean BP, carotid-femoral PWV or augmentation index compared with normal-weight (NW, n=37; 16.7 ± 0.3 yrs; BMI <85^th percentile) (P>0.05). OW demonstrated lower resistance (Z0, 1512 ± 91 vs. 1786 ± 70 dyne x sec/cm⁵) and higher Zc normalized to Z0 (0.13 ± 0.01 vs. 0.11 ± 0.01) and forward wave amplitude (Pf, 48 ± 3 vs. 40 ± 2, mmHg) compared with NW (all P<0.05). Adjusting for age and sex, LVMI correlated with brachial and carotid systolic BP and PP (r=0.26–0.30), Z0 (r=−0.27), Zc normalized for Z0 (r=0.29), and Pf (r=0.32) (all P<0.05). Stepwise multiple regression revealed that BMI (β ± SE; 0.69 ± 0.19; R²=0.26) and Pf (0.23 ± 0.07; R² change=0.11) were the best predictors of LVMI (total R²=0.37, P<0.01). These findings suggest that augmented Pf is a major hemodynamic determinant of increased LV mass with obesity in adolescents.