Liquid phase epitaxial regrowth following laser melting significantly modifies the concentration of point defects in Si, such that peculiar depth distribution of subsequently implanted B arises. At room temperature, a large fraction of B atoms, ∼15%, implanted in laser preirradiated Si, migrate up to the original melt depth. During high temperature annealing, the nonequilibrium diffusion of B is reduced to ∼25% of that measured in unirradiated Si. Both these phenomena are conclusively attributed to an excess of vacancies, induced in the lattice during solidification and to their interaction with impurities and dopant.