Abstract :Deterioration of renal function in patients with acute decompensated heart failure (ADHF) influences the prognosis, suggesting that ADHF should be managed as an acute cardiorenal syndrome. Close collaboration between cardiologists and nephrologists is frequently crucial for management of this condition. It is noteworthy that renal congestion promotes worsening renal function (WRF). High-dose loop diuretics can cause WRF, but are often necessary for treatment of congestion, which is the main symptom of ADHF. However, it is controversial whether WRF associated with diuretic therapy actually has a poor prognosis. In this review, we focus on the mechanism of renal congestion related to WRF in patients with ADHF and on the current status of WRF. We also review the use of loop diuretics to treat ADHF and chronic heart failure, as well as the current role of selective vasopressin-2 receptor antagonist therapy.