We report a patient with compensated congestive heart failure who developed acute anuric renal failure immediately after indomethacin and triamterene had been added to the treatment regimen. Renal function failed to improve promptly with discontinuation of these medications, anuria persisting for 11 days. While it is well known that patients suffering from edematous states are prone to develop renal insufficiency when given nonsteroidal anti-inflammatory agents, it is not generally appreciated that the specific combination of prostaglandin inhibitors with triamterene may carry a particularly high risk of acute renal failure, even in euvolemic subjects.