A magnetically attachable window screen system comprising,a rectangular casement window comprising a casement window frame for removably attaching a rectangular window screen, the casement window frame comprising four window frame sides,the four window frame sides comprising a lower horizontal frame side, an upper horizontal frame side and two opposing vertical frame sides, each window frame side comprising a front perimeter wall and a side perimeter wall, at least one frame magnet attached to the casement window frame at least partly behind the plane defining the front perimeter wall or the plane defining the side perimeter wall, at least one support on the casement window frame for supporting the window screen, the window screen comprising a screen frame comprising four screen bars, the four screen bars comprising a lower horizontal screen bar, an upper horizontal screen bar, and two vertical screen bars, the window screen further comprising at least one screen magnet attached to the window screen frame and positioned to magnetically co-operate with the at least one frame magnet attached to the casement window frame.