The topic of this thesis is the porosity analysis of die-cast aluminum alloy castings. The paper consists of a theoretical and an experimental part. In the theoretical part, high-pressure die casting (HPDC) and its components were briefly described - the casting process, die-casting machines, molds (tools) for casting, die parameters, advantages and disadvantages high-pressure die casting process. After that, an overview of the most common aluminum alloys from which castings are made primarily for the automotive industry was given, and the properties of each alloy were described. At the end of the theoretical part, the common die casting defecets were described, along with methods for identifying and rectifying them to eliminate the errors. The experimental part of the work includes the optimization of one position (casting) that has a porosity problem. The optimization was made during the student internship at the company LTH Metalni Lijev d.o.o. in Benkovac. The problem was solved through several steps, which include optimization of the casting parameters on the die casting machine, creating a simulation and changing the construction of the tool. In the end, castings with much less porosity were obtained. The entire optimization process was done how the problem is solved in practice and the procedure was described in detail in the experimental part of this paper.