The capability of ultrasonic measurements for microstructure characterisation of as-cast and heat-treated ductile irons were investigated, and the data concerning the utilisation of ultrasonic techniques for quality control of ductile irons were provided. Specimens having various amount of nodular graphite were cast by adding different amounts of magnesium to the melt. Beside the as-cast ones, the specimens having various matrix constituents were obtained by applying specific heat treatment procedures. The ultrasonic properties were correlated with amount of nodular graphite and hardness. The results showed that ultrasonic velocity and apparent attenuation. on measurements are well-suited for determining the amount of nodular graphite. The attenuation measurements are more sensitive to the changes in the matrix structure, however, this challenge requires further research.