Abstract: A lamp for illuminating the mouth of a patient which provides an oval pattern of adjustable size and intense illumination which generally conforms to the shape of a patient's mouth, and which is mounted at one end of a flexible tube or gooseneck. The lamp has an elongated filament positioned adjacent to a convex lens, the filament being located between the lens and the focal point of the lens and the distance between the filament and the lens being adjustable to vary the size of the pattern. The illuminating device is provided with a handle located between the flexible tube and the lamp, and the handle has an arm extending outwardly perpendicular to the axis of the filament and an electrical switch for controlling the flow of power to the lamp.