A switch activating hinge comprises a pair of adjacent, pivotally connected hinge leaves, a magnet mounted on one hinge leaf and a switch responsive to the magnet mounted on the other hinge leaf. Tubular casings that are closed at one end receive the magnet and the switch and each casing is inserted into an opening formed in one of the hinge leaves. The casings extend from the rear surfaces of the hinge leaves and the closed ends of the casings define continuous planes with the front surfaces of the hinge leaves, to give the appearance of a conventional hinge. The switch is normally in a predetermined position and it assumes a second position in response to the magnet when the front surfaces of the hinge leaves are in a selected relative orientation, for example, face-to-face relation, as when a door on which the hinge is mounted is closed.