Compacted and spheroidal graphite silicon cast irons generally have slightly hypereutectic compositions when referred to the equilibrium phase diagram. Previous studies have shown that the thermal analysis of these melts often exhibits misleading characteristics that could prevent proper process control. It was the aim of the present work to provide new results, taking into account the carbon equivalent as well as spheroidization and inoculation levels. Overall, the features of slightly and highly hypereutectic melts deduced from previous studies were confirmed, while additional information was obtained concerning the effect of spheroidization and inoculation levels.