Acute renal failure following angiography with contrast agents is known to occur, but the circumstances and frequency of its occurrence are not well described. A retrospective review of consecutive angiographic procedures performed over a six month interval revealed a 12 per cent incidence of renal failure following angiography. The degree of failure was severe in approximately 30 per cent of these cases and was associated with a significant mortality even though renal function usually recovered. The occurrence of renal failure was associated with the presence of renal insufficiency, impaired liver function, diabetes mellitus, hypoalbuminemia and proteinuria at the time of angiography to a statistically significant level. Furthermore, combinations of these factors, particularly preexisting combined renal insufficiency and impaired liver function, were associated with an increased incidence of acute renal failure. It is concluded that angiography poses a significant hazard to patients with underlying medical problems, particularly those involving the excretory routes of the contrast agent.