Si amorphized by Cu implantation has been irradiated by spatially uniform pulses of 7.5 ns duration from a frequency‐doubled neodymium:yttrium aluminum garnet laser. After irradiation the samples were examined by cross‐section transmission electron microscopy. A laterally random pattern of polycrystalline Si patches was found imbedded in amorphous material. At low‐energy densities a considerable fraction of the regrown Si was polycrystalline. With increasing energy density the amount of polycrystalline Si decreased, both at the surface and in total. These results are discussed in terms of the time available for the nucleation of polycrystalline Si at a liquid‐solid interface and the temperature profile in both the liquid and the solid material.