Domain walls naturally arise in any model that has a spontaneously broken discrete symmetry. In the simplest example, symmetry breaking is accomplished by a real scalar field. We investigate infinite domain walls in general relativity using the full Einstein scalar-field equations. We study the gravitational effects on test particles both inside and outside the walls and find that matter is repelled by the walls. Also, we find that there is pressure in the direction perpendicular to the plane of the wall.