Abstract: An illuminated spirit level comprising an elongated bar having a number of apertures wherein bubble tubes are positioned for measurement of the flatness of a surface. An illumination means including lamps, a system of conductor wires, a dual battery configuration connected in series and a switch are contained within the bar. Each aperture is illuminated by a lamp and each lamp communicates with the batteries by conductor wires which are immersed in a channel containing a vibration-dampening fluid. The fluid is supplied through a duct which is accessible from the exterior of the bar. A switch protruding through the exterior of the bar permits power to the lamps.