This article deals with examing the effect of modifier on changes in microstructure of the alloy AlSi7Mg0.3. The content of the experiment was to examine the effect of addition of calcium, stroncium, and antimony to change the morphology of the eutectic silicon in the alloy type of Al-Si (namely AlSi7Mg0.3). Besides changes in the morphology of eutectic silicon was exploring focused on character exlusion modifi-ers within microstructure of the modified alloy. Examination of the microstructure was realized by scan-ning electron microscopy and complemented by EDX analysis of the examined samples.