We have investigated boron diffusion during rapid thermal annealing in Si implanted with boron using an energy of 1keV and a dose of 1×1016cm−2. Two types of samples have been studied: As-implanted and pretreated with excimer laser annealing. For both types an enhanced diffusion of boron has been observed with an enhancement by a factor of 3–5 over the “standard” diffusion. It is suggested that the high concentration of implanted boron is a dominant factor for the diffusion enhancement as compared to the effect of implantation-induced damage. The data indicate that the proximity of the surface can also affect the boron diffusion enhancement.