An LED module is described with a base 10 made out of a heat conducting material. An LED element (32) is arranged in a cavity (11) of the base. A collimator reflector (70) is formed by reflective surfaces (24, 64, 66a). Three of these reflective surfaces (66a, 66b, 64) are provided on a plastic insert (60) received in the cavity (11). A further reflective surface (24) is provided on the base (10)itself. This surface (24) has a straight border line (50). The collimator reflector (70) is arranged to reflect light from the LED (32) so that a cut-off (72) is formed by the straight border line (50). By thus integrating the cut-off, as the most critical optical element, into the base (10) itself, high accuracy is achieved.