The hepatorenal syndrome (HRS) is an acute functional renal failure due to renal arterial vasoconstriction occurring in cirrhotic patients with vascular dysfunction. The renal arterial vasoconstriction is the result of diffuse arteriole vasodilatation. There are two types of HRS, which can be differentiated according to the course and the stage of the renal failure; they have a different prognosis. Liver transplantation remains the standard treatment. Maintenance medical therapy is mainly based on vasopressin analogues. The interest of both dialysis and portosystemic intrahepatic shunt techniques remains to be determined. The prognosis of HRS is poor and in the absence of treatment, onset is usually followed by rapid fatal outcome.