Diabetic nephropathy has become the leading cause of terminal renal failure in all Western nations due to a steady increase of patients with the renal complication of type 2 (non-insulin-dependent) diabetes mellitus. A number of modifiable risk factors have been identified that predispose to and/or accelerate renal disease in patients with diabetes mellitus. Among these, the level of blood pressure, even in the range of normotension according to World Health Organization or Joint National Committee definition, is closely related to the rate of progression of diabetic nephropathy. This has been documented in patients with incipient (microalbuminuric) and in patients with manifest (proteinuric) diabetic renal disease. Consequently, the treatment of even normotensive diabetics has been recommended once microalbuminuria is present, and blood pressure values in the low normal range should be aimed for. The selection of antihypertensive agents is also important, however, since a 'renoprotective effect' has been documented for drugs that interfere with the renin-angiotensin-aldosterone system such as angiotensin converting enzyme inhibitors. Recently, a new class of drugs that selectively inhibits this system by specifically targeting the angiotensin II receptor has been developed. These angiotensin II subtype 1-receptor antagonists are efficacious antihypertensive agents with a side-effect profile similar to placebo. Evidence for a renoprotective effect in patients with diabetic nephropathy from a large controlled clinical trial is still awaited, but data generated in animal experiments and in smaller clinical trials are encouraging. Currently, these drugs are a valuable substitute for angiotensin converting enzyme inhibitors in patients who experience side effects such as intractable cough.