The less rigorous attention to the management of the complications of chronic renal insufficiency (CRI) and its comorbid conditions has potentially tragic consequences. In fact, with early recognition and intervention, many of the complications of CRI and its comorbid conditions can be ameliorated or prevented. We review here the most prevalent, troublesome, and potentially preventable complications and comorbidities of CRI with a View toward developing high-quality, cost-effective strategies for delivering early interventional care, Complications of CRI include malnutrition, anemia, disorders of divalent ion metabolism and osteodystrophy, metabolic acidosis, and dyslipidemia, Important comorbid conditions of CRI are hypertension, diabetes mellitus, and cardiovascular disease. Clinical intuition suggests that early intervention will avert morbidity related to the hypoalbuminemia and other nutritional disorders of CRI, the metabolic acidosis, and the dyslipidemias, but prospective data are lacking at present, Correction of anemia, usually with recombinant human erythropoietin, may be key to the prevention of cardiac disease and other comorbidities of CRI. Incipient disorders of bone and mineral metabolism are managed prospectively using such measures as protein restriction to reduce phosphorus intake, phosphate binders, calcium supplementation, and Vitamin D analogues. Hypertension, whatever its original etiology, is clearly an important risk factor for the progression of kidney failure and for the development of diffuse vascular disease; appropriate and aggressive treatment is essential. In patients with diabetic nephropathy, the principles of both primary and secondary prevention have been validated in several large trials of glycemic and blood pressure control. The seeds of these insidious, challenging, and costly comorbid conditions are sown very early in CRI, at a time when they are-in theory-most amenable to intervention. We therefore must be as proactive as possible in the timely implementation of relatively simple therapies that have the potential to prevent some of these adverse outcomes of CRI. (C) 2000 by the National Kidney Foundation, Inc.