The problem of product-size distribution exiting a crystallizer is addressed theoretically and experimentally. The distribution function of thee particle size is solved and demonstrated experimentally as a function of fines destruction, solids content of feed, particle circulation ratio, feed particle sizes, particle concentration. Theoretical tools are given for estimation of various important parameters such as distribution moments, rate of growth, rate of nuclei production and particle-size distribution. A good agreement is shown between the theoretical model and the experimental results.