Low-pressure mercury vapor discharge lamp comprising a discharge vessel (10) having a first and a second end portion (12a, 12b), the discharge vessel (10) containing mercury and a rare gas, wherein the end portions (12a, 12b) each support an electrode (20a,20b) arranged in the discharge vessel (10) for initiating and maintaining a discharge in the discharge vessel (10), wherein an electrode shield (22a,22b) substantially encompasses at least one of the electrodes (20a,20b), and wherein said electrode shield (22a,22b) comprises an inner wall (23a) and an outer wall (24a), said walls (23a,24a) being spaced apart.