The most attractive properties of magnesium alloys to industry are their light weight, strength to weight ratio, higher strength in thin sections, high quality surface finish and precise dimensions of cast components [1-4]. A problem, however, has been reported by the magnesium die casting industry involving soldering , although it is not as severe as in aluminium high pressure die casting (HPDC). Unlike aluminium HPDC in which soldering has received a great deal of attention [6-14], little is known about soldering in HPDC of magnesium alloys. The primary aim of the experiments was to understand the role of manganese on the soldering reaction. Results from the HPDC trials are also reported in this paper.