Chronic kidney diseases affecting the nephron mass are characterized by a progressive decline of glomerular filtration rate (GFR) occurring irrespectively of the cause of the renal damage once a critical number of nephrons has been lost. Current clinical research efforts focus on preventive strategies to slow down or arrest disease progression. Systemic hypertension and glomerular hyperfiltration with resulting proteinuria and activation of vasoactive, profibrotic and proinflammatory systems have been identified as major causes of further nephron damage. Angiotensin converting enzyme (ACE) inhibitors are not only potent antihypertensive agents but also reduce proteinuria, glomerulosclerosis and tubulointerstitial fibrosis via reduction of the local angiotensin tone in the kidney, and have been demonstrated to slow down renal failure progression in adult patients. Childhood-onset ESRD is a rare but particularly devastating disease with poor life expectancy and quality of life. Chronic renal failure in children is caused by a different spectrum of nephropathies than in adults, with a preponderance of congenital or inherited abnormalities. Since hypertension, proteinuria and tubulointerstitial fibrosis are also common in pediatric chronic renal failure, there is a rationale for pharmacological renoprotection by ACE inhibition in children. The prospective, randomized European clinical trial launched by our consortium will provide the critical mass to assess several aspects of renoprotective therapy in children. Specifically, the trial is designed to address the following scientific objectives: