The pathogenesis of progressive renal damage is most probably multifactorial. Whatever the mechanisms involved in renal disease progression, the existence of a "point of no return" has been hypothesized, that is, a stage of structural and functional damage beyond which progression of renal disease occurs independently of dietary measures and/or pharmacological treatment. In experimental animals, dietary protein and phosphate restriction is not fully successful in ameliorating the progression of functional deterioration if administered when renal injury is severe and long standing. Similarly, late treatment with various pharmacological agents (mainly antihypertensive drugs) is less effective than early administration of the same substances. A serum creatinine of 176 mumol/L seems a critical point discriminating the results of either dietary protein and phosphate restriction or antihypertensive treatment in patients with chronic renal disease. The protective effects of both dietary and nondietary intervention seem to be most effective when at least 50% of the residual renal mass is still functioning. The extent to which glomerular sclerosis, vascular hyalinosis, and interstitial fibrosis have already developed can probably blunt or avert the expected results of treatment. Some clinical tests may identify those patients who would benefit from measures such as the reduction in glomerular hemodynamic stress, the long-term inhibition of the renin-angiotensin system, and the aggressive treatment of systemic hypertension. The continuous search for a rational preventive treatment before the disease process has reached the "point of no return" will undoubtedly constitute a formidable task for the modern nephrologist.