Abstract: A luminous signalling device comprises a body made of transparent synthetic material, basically in the form of a plate having two larger faces set opposite one another, at least one of which carries an image. A plurality of LED devices of the SMD type which emit white light is coupled externally to at least one of the walls that define the peripheral edge of the aforesaid plate body. The arrangement is such that the rays of white light coming out of the LED devices undergo multiple total reflections within the plate body, which thus functions as a light guide. In areas corresponding to selected areas of the image, the face of the plate body is made up of diffusing optical elements designed to diffuse outwards the rays of light that are incident on said areas within the body.