Acute renal and hepatic failure can occur for many reasons. The hepatorenal syndrome is acute renal failure of unknown cause developing in a patient with chronic liver disease, usually cirrhosis. The pathogenesis is functional in nature due to a combination of redistribution of fluid between compartments and intrarenal events reducing renal blood flow (activation of the renin-angiotensin system, increased renal sympathetic activity, and a decrease in vasodilating and increase in vasoconstricting prostaglandins). Management of combined renal and hepatic failure consists of measures to control the uraemia and the effects of hepatic dysfunction. Haemodialysis is accompanied by a number of specific problems such as maintenance of cerebral perfusion and anticoagulation. At present the best dialysis mode is continuous haemodiafiltration using a biocompatible membrane. The prognosis of the hepatorenal syndrome is poor and depends on recovery of hepatic function. Liver transplantation may be required.