The damage produced by high current density ∿l0µA/cm2 implants of 120 keV P+ into <111> and <100> silicon wafers, 500 °m thick, has been investigated in the fluence range 1×l01 5/cm2-l×l016 /cm2 by ion channeling and by transmission electron microscopy. For both orientations the thickness of the damage layers increases with the fluence up to 2×1015 /cm2 and then decreases. The rate of regrowth is a factor two faster for the <100> with respect to the <111> oriented Si crystals. Similar ratios have been found in pre-amorphized samples and irradiated with Kr+ ions in the temperature range 350°C-430°C. The TEM analysis reveals the presence of hexagonal silicon and of twins in small amounts for both orientations. The beam induced epitaxial growth depends also on the species present in the amorphous layer. A comparison between self-annealing and beam annealing in Si <100> preamorphized with Ar+ or P+ shows a noticeable retardation of the growth rate in the presence of Ar+.