The amorphization and recrystallization of tin‐ion‐implanted gallium arsenide were studied by cross‐sectional transmission electron microscopy. Amorphization occurred in the sample implanted at a dose of 1014ions/cm2. The interface between the amorphous region and the crystalline matrix is not flat. The amorphous region recrystallizes epitaxially with microtwin formation at 673 K. The amorphous‐crystalline interface in the sample implanted at a dose of 1016ions/cm2is flat. In the deep region of this sample a solid‐phase epitaxial growth without microtwin formation is observed after annealing at 673 K. These structural changes were compared with the nuclear energy loss (damage energy) distribution simulated by thetrimcode. It is concluded that the amorphization of the sample implanted at a dose of 1014ions/cm2is induced by the accumulation of damage energy; on the other hand, the amorphization of the sample implanted at a dose of 1016ions/cm2cannot be explained only by this process. The contribution of stress at the amorphous‐crystalline interface is suggested.