Abstract: A light guide for illuminating a keyboard or keypad from behind comprises a transparent grid-like plate having an array of apertures in each of which is accommodated a respective key of the keyboard/keypad. The transparent plate comprises an integral lens aligned with a reflector for directing light from an external source into the plane of the plate. Various plane reflecting surfaces are provided for reflecting the light in a localized path completely surrounding each of the apertures. This arrangement enables the keys to be illuminated with a high degree of uniformity using only relatively few distributed light sources.