Background: Themechanism of hypertension in appropriate weight for gestational age (AGA) premature infants is unknown. Common carotid arterial (CCA) wave intensity (WI) analysis may detect vascular changes associated with hypertension prior to conventional methods. Methods: In 47 AGA ex-premature young adults (exprems, 18.6± 0.6 yrs, mean±SD) and 38 age-matched controls, 10 beat cine-loops of CCA velocity (U) and diameter (D) were acquired using echocardiography, with edge-detection, ensemble averaging and smoothing of signals. Diameter was scaled to Sphygmocor-determined CCA pressure (P), and CCA WI was derived as the product of the rates of change of P and U, with separation into forward and backward components. Pressure ( P) and velocity ( U) changes associated with forward and backward waves were calculated after wave separation. Pulse wave velocity (PWV) and augmentation index (AI) were obtained with Sphygmocor. CCA compliance was calculated. Results: Carotid systolic (109± 11mmHg vs 99± 15mmHg, p= 0.001) and mean (85± 8mmHg vs 79± 7mmHg, p= 0.001) blood pressures were greater in ex-prems. WI profiles displayed an initial-systolic forward compression wave (FCW) associated with LV ejection and a mid-systolic backward compression wave (BCW) arising from vascular reflection of FCW. Although FCW area was no different, BCW area was increased in ex-prems (p= 0.05). The P of BCW was increased in ex-prems (p= 0.007), and the BCW:FCW P ratio was 14% higher, indicative of increased wave reflection (p< 0.001). By contrast, PWV,AI, pulse pressure andCCAcompliance were not different. Conclusions: AGA ex-premature adolescents have increased CCA wave reflection indices as determined by WIA, despite normal conventional vascular function.