CRS is a common problem in patients with advanced heart failure. Arterial underfilling with consequent neurohormonal activation, systemic and intrarenal vasoconstriction, and salt and water retention cause the main clinical features of CRS which include a progressive decline in renal function, worsening renal function during treatment of heart failure (HF) decompensation and resistance to loop diuretics. Impaired renal function in HF patients often reflects more advanced stages of cardiac failure, and thus is associated with a worse prognosis. However, a transient fall in glomerular filtration rate may be a result of successful treatment of congestion, and thereby might not be associated with decreased survival in HF patients. This review covers basic pathophysiological mechanisms underlying the CRS and current trends in practical approaches to treat these patients.