Abstract: The invention relates to a metal halide lamp (1) combining a high luminous efficacy and a high red rendering. This is realized by a lamp comprising a discharge vessel (10) with a ceramic wall, the discharge vessel enclosing a discharge space (11) which contains two electrodes and an ionisable filling, which filling contains at least 20 mol % of a Ca-halide, and one or more halides selected from the group of T1 and the rare earths, wherein the ionisable filling comprises Mg-halide, Mn-halide, or a mixture thereof in a molar quantity of at least 5 mol %, and preferably between 10 and 15 mol % of the total quantity of halides.