Lighting device for vehicles, in particular rear lamp, having - a light unit for the generation of a given light function, comprising a number of light sources and an optics unit, wherein the optics unit has a light guide with means of deflection for light of the light source coupled into the same, and - a reflex reflector unit for the generation of a reflex reflector function, wherein - the light guide is embodied as a low profile light guide and - the means for the deflection of the light are arranged in a distributed manner on and/ or in the low profile light guide, that a first light beam emitted by the light source and coupled into a narrow side of the low profile light guide is coupled out of a front narrow side of the low profile light guide to generate the given light function, characterized in that - the low profile light guide is arranged in the main radiation direction in front of the reflex reflector unit, - a second light beam radiating in from the outside passes through the front flat side and a rear flat side of the low profile light guide, hits the reflex reflector unit, and is reflected back in the main radiation direction from the same through the rear flat side and the front flat side of the low profile light guide to generate the reflex reflector function, - a number of diffusion optics elements (25, 25') are arranged on the rear flat side of the low profile light guide as a means for deflection of the first light beam, so that the coupled-in first light beam hitting the diffusion optics elements (25, 25') is reflected in the direction of the front flat side for the coupling out from the same in the main radiation direction, and - the diffusion optics elements (25, 25') are arranged at a distance relative to one another, so that diffusion optics-free faces are formed on the rear flat side for the passing of the second light beam. - a light unit for the generation of a given light function, comprising a number of light sources and an optics unit, wherein the optics unit has a light guide with means of deflection for light of the light source coupled into the same, and - a reflex reflector unit for the generation of a reflex reflector function, - the light guide is embodied as a low profile light guide and - the means for the deflection of the light are arranged in a distributed manner on and/ or in the low profile light guide, that a first light beam emitted by the light source and coupled into a narrow side of the low profile light guide is coupled out of a front narrow side of the low profile light guide to generate the given light function, - the low profile light guide is arranged in the main radiation direction in front of the reflex reflector unit, - a second light beam radiating in from the outside passes through the front flat side and a rear flat side of the low profile light guide, hits the reflex reflector unit, and is reflected back in the main radiation direction from the same through the rear flat side and the front flat side of the low profile light guide to generate the reflex reflector function, - a number of diffusion optics elements (25, 25') are arranged on the rear flat side of the low profile light guide as a means for deflection of the first light beam, so that the coupled-in first light beam hitting the diffusion optics elements (25, 25') is reflected in the direction of the front flat side for the coupling out from the same in the main radiation direction, and - the diffusion optics elements (25, 25') are arranged at a distance relative to one another, so that diffusion optics-free faces are formed on the rear flat side for the passing of the second light beam.