Abstract: A high-pressure metal vapor discharge lamp comprising an outer tube, a light emitting tube located within the outer tube and made of a light-transmissive ceramics material, and a fuse electrically connected in series with the light emitting tube, in which said fuse has such a blowing characteristic as given by the following equation and at a rated output during the lighting of the lamp the density of a current through the fuse is not more than 23.9 A/mm.sup.2 :log T.sub.1 <AlogI+BA=-1.02.times.10.sup.-2 (D.sup.2 t)-0.885B=2.64.times.10.sup.-2 (D.sup.2 t)+1.01T: required blowing time (seconds) of the fuseI: blowing current (A) of the fuseD: inner diameter (mm) of the light emitting tubet: wall thickness (mm) of the light emitting tube.

Abstract: A metal vapor discharge lamp has a light emitting tube of translucent ceramics which includes a straight tube section of a predetermined diameter and a pair of tube end sections having their diameter gradually decreased from the straight tube section. The light emitting tube is formed such that a height from a corresponding sealing member to a boundary of the straight tube section and tube end section is greater than a height from the sealing member to the lower end of a radiator section of a discharge electrode and that a minimum radius of the tube end section of the light emitting tube is greater than an outer radius of the radiator section of the discharge electrode by a difference of 1.5 mm or less left therebetween.