Hepatorenal syndrome (HRS) is defined as a functional renal failure in patients with liver disease that features morphologically intact kidneys, where regulatory mechanisms have minimized glomerular filtration and maximized tubular resorption and urine concentration. The syndrome occurs almost exclusively in patients with ascites. Type 1 HRS develops as a consequence of a severe reduction of effective circulating volume due to both an extreme splanchnic arterial vasodilatation and a reduction of cardiac output. Type 2 HRS is characterized by a stable or slowly progressive renal failure so that its main clinical consequence is not acute renal failure, but refractory ascites, and its impact on prognosis is less negative. Liver transplantation...