An operating arrangement for an electrically operated window screening device of the type comprising a flexible screening body (1) which is rolled up on a roller (2) positioned in or at an upper horizontal main frame or sash member of the window and in a free end is connected with a bottom rail (4) extending the width of the window. The operating arrangement comprises a cord or string-formed pull-element (12, 13; 24) acting on the screening body and being wound on a winding device (11; 22, 23) positioned at a lower main frame or sash member, with an accompanying electrical drive motor (9). For moving the screening body (1) in an unrolling direction, the pull-element (12, 13; 24) is guided from the winding device along both opposite main frame or sash side sections of the window for connection with the bottom rail (4), whereas the movement of the screening body in the opposite rolling up direction is effected by a spring force acting on said roller (2) during simultaneous unwinding of the pull-element from the winding device. The pull-element (12, 13; 24) may be connected with a separate bar profile (5) designed for after-mounting on a bottom rail (4) for a screening device already installed.