Abstract: A metal vapor discharge lamp comprises a light-emitting tube filled with bismuth together with mercury, a rare gas, iron and a halogen in the range of 1/20-6/1 in terms of the gram atom ratio of bismuth to iron (Bi/Fe). A metal vapor discharge lamp also comprises a long light-emitting tube having an inner diameter D of 18-35 mm, equipped with a pair of electrodes and having an electrode interval L of 750 mm or greater, filled with bismuth together with mercury in a sealed amount of 0.6-2.0 mg per cc of the internal volume of the light-emitting tube, a rare gas, iron and a halogen in the range of 1/20-6/1 in terms of the gram atom ratio of bismuth to iron (Bi/Fe).