Diabetic nephropathy is a common cause of end stage renal failure. Patients ultimately require dialysis or transplantation and endure a poor quality of life in association with increased mortality. Due to the quantitative significance of this problem there is also a considerable financial burden. It has been generally accepted that once nephropathy is established it is irreversible although aggressive anti-hypertensive treatment can delay its progression. More recently there have been numerous reports proposing a specific renal protective role of certain drugs. In this article we review the current literature on the use of angiotensin converting enzyme inhibitors in diabetic nephropathy. There is strong evidence that the use of ACE inhibitors in diabetic nephropathy (in the presence or absence of hypertension) slows the progression of deterioration in renal function and may even arrest its progression if detected at the microproteinuric stage.