A roof window configured to be installed in an inclined roof, said roof window comprising a frame and a sash, each having a top member (8, 9) and a bottom member (4, 5) extending in a longitudinal direction, and two side members (6, 7) extending in a height direction substantially perpendicular to the longitudinal direction, the sash being rotatably connected to the frame, such that a rotating opening movement of the sash in relation to the frame about a pre-defined hinge axis brings the sash from a closed position to an open position, said pre-defined hinge axis being parallel to the bottom members of the frame and sash, said rotating opening movement forming an opening angle (b) between the frame and the sash in the open position, and at least one opening restrictor comprising an arm rotatably connected to a frame or sash member and having a gripping mechanism configured to engage with a gripping element connected to an opposing sash or frame member so as to limit the opening of the sash, the arm with the gripping mechanism being configured to assume at least a disengaged condition and an engaged condition in which the gripping mechanism is in engagement with the gripping element and in which the opening of the sash is limited to a maximum limited angle, characterised in that the arm of each opening restrictor is connected to a bottom member (5, 4) of the sash or the frame, and that the gripping element is connected to the opposing bottom member (4, 5) of the frame or the sash, such that said arm is hidden in a space provided between the frame and the sash, leaving said opening restrictor invisible in the closed position of said sash and in the open position of said sash within a pre-defined opening angle. a frame and a sash, each having a top member (8, 9) and a bottom member (4, 5) extending in a longitudinal direction, and two side members (6, 7) extending in a height direction substantially perpendicular to the longitudinal direction, the sash being rotatably connected to the frame, such that a rotating opening movement of the sash in relation to the frame about a pre-defined hinge axis brings the sash from a closed position to an open position, said pre-defined hinge axis being parallel to the bottom members of the frame and sash, said rotating opening movement forming an opening angle (b) between the frame and the sash in the open position, and at least one opening restrictor comprising an arm rotatably connected to a frame or sash member and having a gripping mechanism configured to engage with a gripping element connected to an opposing sash or frame member so as to limit the opening of the sash, the arm with the gripping mechanism being configured to assume at least a disengaged condition and an engaged condition in which the gripping mechanism is in engagement with the gripping element and in which the opening of the sash is limited to a maximum limited angle, characterised in that the arm of each opening restrictor is connected to a bottom member (5, 4) of the sash or the frame, and that the gripping element is connected to the opposing bottom member (4, 5) of the frame or the sash, such that said arm is hidden in a space provided between the frame and the sash, leaving said opening restrictor invisible in the closed position of said sash and in the open position of said sash within a pre-defined opening angle.