The interdependence of cardiac and renal dysfunction has emerged as a focus of intense interest in heart failure management due to the substantial associated morbidity and mortality. Captured in the clinical entity known as cardiorenal syndrome, recent definitions afford discussion of the acute and longitudinal evaluation and management of these patients. This article discusses potential pathophysiologic mechanisms of cardiorenal syndrome, epidemiology, inpatient and long-term care (including investigational therapies and mechanical fluid removal), and end-of-life and palliative care.