Substantial reduction of functioning nephrons from any origin is followed by a relentless progression to chronic renal failure. This progression continues long after the acute nephropathy and its initiating events have subsided. Glomerular hypertension and hyperfiltration are the major contributors to this progressive nephron loss. Studies on the adverse effects of hemodynamic changes and attempts to define the modalities that slow the rate of progression of renal disease have been among the dominant trends in modern nephrology. Numerous animal studies as well as recent clinical trials indicate that blockade of the renin angiotensin system effectively retards progression of nephropathy from diverse origins.