We have performed computer simulations of simultaneous and sequential ion bombardment and epitaxial growth. In agreement with recent reflection high‐energy electron diffraction (RHEED) measurements on Si, we observe ion‐induced RHEED oscillations, a cancellation of RHEED oscillations during simultaneous equal‐rate ion bombardment and growth, and a reversal of growth‐induced roughening by subsequent ion bombardment. Comparison between simulations and measurements indicate that a model of the ion/surface interaction characterized by the creation of mobile vacancies with minimal preferential sputtering is sufficient to simulate all the RHEED measurements.