Recent evidence suggests that renal prostaglandins play a major role in the control of renal hemodynamics and function in patients with advanced liver disease. The available data suggest that alterations in renal prostaglandin metabolism participate in the pathogenesis of at least three prominent renal complications of liver disease: sodium retention, impaired renal diluting ability, and the hepatorenal syndrome. Nonsteroidal anti-inflammatory agents that inhibit cyclooxygenase activity favor sodium retention and diminish renal plasma flow and glomerular filtration rate in patients with decompensated cirrhosis. The clinical caveat emerging from these observations is that nonsteroidal anti-inflammatory agents, which inhibit cyclooxygenase activity, should not be prescribed for sodium-retaining patients with decompensated liver disease.