Abstract: A window screen or shade, in particular for motor vehicles, includes a wind-up roller biassed in the wind-up direction that is rotatably journalled in a base and on which shade or screen web is secured with one end. The other edge of the web is mounted in an end rail, which is engaged by at least one extension element of an extension structure located in the vicinity of the wind-up roller, in order to unwind the web counter to the biassing of the spring mechanism for the wind-up roller. To enable dispensing with additional guide elements for the end rail, which support the window shade in the direction at right angles to the spread-open web, the extension element is substantially rigid, at least in a direction at right angles to the plane of the web defined by the extended web, and when the web is extended can move in a plane parallel to this plane of the web.