A roof window comprising a frame, a sash, and a pane, in which the frame comprises a set of frame members including a top frame member, two side frame members (22, 23) and a bottom frame member and the sash comprises a set of sash members including a top sash member, two side sash members (32, 33) and a bottom sash member, each frame and sash member defining a longitudinal direction, and in which the roof window furthermore comprises a hinge assembly configured to allow the sash to be tophung about a substantially horizontal first hinge axis (α) in a first operational condition in a mounted condition of the roof window and comprising a hinge unit with a frame hinge part connected to or connectable to at least the top frame member and a sash hinge part connected to at least the top sash member, in which the hinge assembly comprises a coupling unit connected to or connectable to the frame and configured to be connected to the hinge unit in the mounted condition of the roof window, and in an installation condition of the roof window, the hinge unit is connected to the sash and the coupling unit is connected to the frame, wherein the coupling unit and the hinge unit are configured to assume the following positions relative to each other: i) at least one intermediate position; and ii) a final position, corresponding to the mounted condition of the roof window, wherein the coupling unit comprises a top frame coupling plate connected to the top frame member, the top frame coupling plate being provided with coupling plate engagement means (964f, 964g; 964h, 964i, 964j) configured to cooperate with counterpart frame hinge part engagement means of the frame hinge part, characterised in that the coupling plate engagement means comprise a hook element comprising an arm with a hook and connected to a base section of the top frame coupling plate in a rotational joint, and wherein the frame hinge base plate comprises a protrusion constituting the frame hinge part engagement means and configured to cooperate successively with at least one intermediate engagement portion (964f; 964h, 964i) and a final engagement portion (964g; 964j) of said hook element, and in that the hook element is biased towards a locking position in which the protrusion of the frame hinge base plate is in engagement with the final engagement portion, the bias being provided by a spring accommodated with one end in a spring-receiving opening in the arm and with another end in a spring-receiving opening in the base section, the spring passing through an opening allowing movement of the spring during movement of the hook element. the frame comprises a set of frame members including a top frame member, two side frame members (22, 23) and a bottom frame member and the sash comprises a set of sash members including a top sash member, two side sash members (32, 33) and a bottom sash member, each frame and sash member defining a longitudinal direction, and in which the roof window furthermore comprises a hinge assembly configured to allow the sash to be tophung about a substantially horizontal first hinge axis (α) in a first operational condition in a mounted condition of the roof window and comprising a hinge unit with a frame hinge part connected to or connectable to at least the top frame member and a sash hinge part connected to at least the top sash member, in which the hinge assembly comprises a coupling unit connected to or connectable to the frame and configured to be connected to the hinge unit in the mounted condition of the roof window, and in an installation condition of the roof window, the hinge unit is connected to the sash and the coupling unit is connected to the frame, wherein the coupling unit and the hinge unit are configured to assume the following positions relative to each other: i) at least one intermediate position; and ii) a final position, corresponding to the mounted condition of the roof window, wherein i) at least one intermediate position; and ii) a final position, corresponding to the mounted condition of the roof window, wherein the coupling unit comprises a top frame coupling plate connected to the top frame member, the top frame coupling plate being provided with coupling plate engagement means (964f, 964g; 964h, 964i, 964j) configured to cooperate with counterpart frame hinge part engagement means of the frame hinge part, characterised in that the coupling plate engagement means comprise a hook element comprising an arm with a hook and connected to a base section of the top frame coupling plate in a rotational joint, and wherein the frame hinge base plate comprises a protrusion constituting the frame hinge part engagement means and configured to cooperate successively with at least one intermediate engagement portion (964f; 964h, 964i) and a final engagement portion (964g; 964j) of said hook element, and in that the hook element is biased towards a locking position in which the protrusion of the frame hinge base plate is in engagement with the final engagement portion, the bias being provided by a spring accommodated with one end in a spring-receiving opening in the arm and with another end in a spring-receiving opening in the base section, the spring passing through an opening allowing movement of the spring during movement of the hook element.