Left ventricular hypertrophy (LVH) is related to a 1,000-fold increased risk of cardiovascular morbidity and mortality in young adults with end-stage renal disease (ESRD) treated with hemodialysis (HD) or peritoneal dialysis. We report a series of 17 children (5 girls, 12 boys), with a median (range) age of 11 (2-18) years, all treated by HD, who presented with an increased left ventricular mass (LVM) index of 54.8+/-4.5 g/m2.7 at onset of HD and reached 36.2+/-2.6 g/m2.7 (mean+/-SEM, P<0.0001) at last follow up. Over the observation period, systolic (P<0.0001) and diastolic (P<0.0001) blood pressure (indexed for height, gender, and age) decreased and hemoglobin (+2.8 g/dL; P<0.0001) increased compared to initial values. Only BP as well as plasma protein level at onset of HD session correlated with LVM in multiple correlation analysis. In conclusion, increased LVM is a common feature in pediatric patients with ESRD. Normalization of BP and reduction of the extracellular volume (represented by plasma protein at onset of HD session) are key points in reducing LVH during HD in children.