Eutectic nodular cast iron was quenched at various stages during solidification process. Three-dimensional size distribution of nodular graphite in those samples was measured by Lord and Will's method. Solidification of nodular graphite cast iron was numerically simulated using various nucleation models and diffusion controlled growth model. Calculated nodule size and graphite volume fraction by carefully adjusting nucleation frequency constant resultd in the same order of magnitude as those obtained by measurements. However, it was not possible at this stage to obtain agreement on the total distribution curve between experiment and calculation with any of the nucleation model adopted.