A review of the pathophysiology of variceal bleeding, with a discussion of the pathogenesis of portal hypertension, formation of varices, and bleeding from varices. Portal hypertension results from increases in portal flow and portal vascular resistance. The factors increasing portal blood flow are primarily humoral. Resistance to portal flow has fixed and variable components. Elevated portal pressure leads to variceal formation. Variceal bleeding is dependent on portal pressure, variceal size, and variceal wall thickness.