Nowadays die-casting is one of the best of metal casting system. Die-casting comparing with the other casting methods is cost preferably, the savings may be 20% of the metal needed for the casting and cost savings of foundry production can be around 30%. In this work we have measure hardness of Al-Si alloy respect to its Fe content. In our experiments we have used digital microhardness tester CV - 400D respect to the Vickers hardness test. Samples were processed in dentacryl. We have made a conclusion that content of the Fe in the alloy have some influence on the product’s hardness. Even insignificant difference in chemical composition of the casting products will lead to different hardness characteristics of the products.