In article results of quantitative and qualitative analysis of graphite in gray cast iron have been presented. Specimens from six melts that had been realized in different way, taking into account charge materials as well as melting practice were tested. Melts I and II had been made in traditional way from special pig iron Sorel, III from steel-making pig iron, IV, V and VI are synthetic cast iron made from steel scrap and graphite scrap. The four pictures of structure that had been made on casting specimen of 30mm diameter for each melt as well as for special and steel-making pig iron were analyzed. The quantitative and qualitative analysis has been made using MultiScan v13.01 computer software. Several conclusions from the comparative analysis of histogram taking into account differences between cast irons and similarity of cast irons to pig iron for melts I, II and III have been presented.