Heart failure (HF) and renal dysfunction frequently coexist; this combination is commonly referred to as the "cardiorenal syndrome." The intersection of cardiac and renal dysfunction has important therapeutic and prognostic implications in patients with HF. Approximately 60% to 80% of patients hospitalized for HF have at least stage III renal dysfunction; this comorbid renal insufficiency (RI) is associated with significantly increased morbidity and mortality risk. Comorbid RI can result from intrinsic renal disease and inadequate renal perfusion. HF and RI stimulate neurohormonal activation, increasing preload and afterload and reducing cardiac output. Inotropic agents augment this neurohormonal activation. Managing cardiorenal patients requires successful negotiation of the delicate balance between adequate volume reduction and adequate renal function. There is a compelling need for additional studies in this patient population.