Abstract: Method and apparatus for producing light metal alloys, in particular aluminum alloys, in which the desired alloying elements are first introduced into a vacuum furnace which is then evacuated, whereafter light metal melt is introduced into the furnace chamber by suction in the form of a free-falling metal jet which is thereby subjected to a vacuum treatment for reducing the contents of impurities, such as hydrogen, sodium, oxides and other non-metallic particles, therein. The free-falling metal jet is given such a configuration with respect to composition and flow pattern, such an average length as well as such velocity and direction that the alloying elements are readily dissolved and mixed into the melt in the vacuum furnace, whereby an alloy of desired quality is ready for casting immediately after termination of the vacuum treatment and alloying process.