A screen system for use with a sliding panel of a window or door is used to screen an opening as the sliding panel or door is opened. The screen is attached to the edge of the sliding panel adjacent the opening, and is wound onto a spindle. The spindle is rotatably mounted adjacent the screen opening around which the screen is wound so that the screen can be unwound from or wound onto the spindle. A cord is connected between the sliding panel and the spindle pulley via an idler pulley. In this arrangement the spindle is caused to rotate so as to wind the screen back onto the spindle as the sliding panel is slid towards the closed position. Whilst the screen is wound off the spindle, the cord is wound onto the spindle pulley and vice versa. As the A tension adjustment arrangement can also be provided that is configured to adjust the tension in the cable as the screen is wound and unwound from the spindle due to the change in diameter of the cord around the spindle pulley.