In this review, we emphasize three aspects of the regrowth of ion‐implanted amorphous Si layers: (1) orientation dependence of the regrowth kinetics, (2) impurity effects on the regrowth kinetics, and (3) impurity distribution due to regrowth. To account for the orientation dependence there are at least three proposed models: (1) geometric model, (2) stress relaxant model, and (3) surface reconstruction model. Each of these models is discussed here. For amorphous Ge regrowth, the characteristics are similar to those of Si. Parallels are drawn whenever possible. An example is given to illustrate the use of ion‐implanted‐regrowth process to modify the crystallinity of thin layers.