Ascites formation in patients with cirrhosis of the liver is dependent on local factors that preferentially localize any fluid retention to the peritoneal space and systemic factors that favor renal retention of salt and water. The local factors are largely related to adaptive changes in the hepatic sinusoids and mesenteric capillaries in response to an increase in hydrostatic pressure. The systemic factors reflect the disturbance in volume homeostasis evident in patients with cirrhosis and are largely explained by the neurohumoral consequences of a decreased peripheral vascular resistance.