A model is presented which describes statistically the growth and dissolution of oxygen precipitates and stacking faults by a set of rate equations (RE) and a Fokker-Planck equation (FPE). The REs allow an accurate description of very small precipitates and stacking faults while the FPE allows an efficient treatment of the large ones. The influences of interstitial oxygen diffusion, precipitate stress, and point defects are considered in the model. The system of nonlinear coupled partial differential equations (PDE) formed by the REs, FPEs, and the continuity equations of interstitial oxygen and of the point defects is solved by a numerical method especially suited for the structure of this system. The model is applied to the simulation of HI-LO-HI anneals which are typically performed by wafer manufacturers to produce a "defect-free zone" and internal gettering (IG) sites. The results are verified by comparison with experimental data reported in the literature.