The coarsening of a polydisperse set of N particles is studied by computer simulation. The main steps of the simulation are the following : generation of a set of N (typically 20 000) particles according to an a priori model of the particle size distribution, and subsequent transfers of molecules from one particle to another according to predetermined growth rules. As an application, we consider the Ostwald ripening process. In this case, the exchange of molecules between small and large particles is governed by Kelvin＇s equation. The evolution of the average particle radius and of the size distribution is studied both in the stationary and nonstationary regimes. The typical characteristics of the stationary regime predicted by the Lifshitz-Slyozov-Wagner theory are recovered. For a more realistic initial log-normal size distribution, it was found that during an increase in average radius of about a factor of 4.3, the stationary regime was not yet attained. Results are also reported for the combined effects of Ostwald ripening and membrane resistance.