Amorphous layers, approximately 4000 A˚ thick, were formed on single‐crystal Si samples by implantation of28Si ions at LN2substrate temperature. Channeling‐effect measurements with MeV4He ions were used to measure the thickness of the amorphous layers and to measure the subsequent epitaxial regrowth on the underlying crystalline substrates. For annealing temperatures between 450 and 575 °C, the growth rate showed a strong dependence on the substrate orientation with ⟨100⟩‐oriented samples exhibiting about a 25 times higher growth rate than ⟨111⟩‐oriented samples. Measurements of the growth rate on a series of samples cut in 5° angular increments show that there is a monotonic decrease from the ⟨100⟩ to the ⟨111⟩ orientation. A simple model is proposed to explain the observed orientation dependence.