The invention refers to a lighting device (10) for a support or supply system (T) for medical-electrical devices, respectively, having: a light rack (1) for carrying an illuminant (2), at least one illuminant (2) attached to the light rack, a light cover (3) for covering the illuminant, and fixing means (4) for fixing the rack (1) to the medical support or supply system, respectively, wherein an assembly of the light rack (1), the at least one illuminant (2), and the light cover (3) generates a flat and space-saving profile for the lighting device (10), and wherein the lighting device (10) is designed for being retrofitted on a substantially horizontal surface of the support or supply system (T), respectively, to serve as floor lighting or ceiling lighting.