A pivot hinge for roof windows with a sash pivoting around the axis located between the upper and the lower member of a window, has a balancing system, which ensures the state of equilibrium of a window sash when its centre of gravity is located outside the sash rotating axis and the friction spring of the hinge is unable to hold the sash pivoted in each its position. At the same time the window fittings, its assembly, installation in a roof and its appearance remain unchanged. Also the method of separating of both hinge parts (taking a sash out of a window frame) remains unchanged.