This paper reviews the role of the actin cytoskeleton in the establishment and maintenance of surface membrane structure and function in all epithelial cells. It describes in detail certain interactions between the actin cytoskeleton and the surface membrane. Recent studies show that ischemia and/or ATP depletion will rapidly disrupt the actin cytoskeleton, an important event in ischemia-induced cell injury. Finally, the review examines specific functional and structural interactions between the actin cytoskeleton and the surface membrane.