Physiological insights gained in the 1980s into mechanisms of disease progression in experimental chronic nephropathies established the basis for therapeutic interventions to retard the progression of chronic renal disease in humans. In the 1990s, several large-scale clinical trials have confirmed the renoprotective effects of angiotensin-converting enzyme inhibitors in diabetic and nondiabetic nephropathies. Other studies have afforded strong support for the efficacy of dietary protein restriction in certain settings and underscored the importance of blood pressure control in proteinuric individuals. These interventions form the core of current strategies designed to preserve kidney function in patients with chronic renal disease.