Ion-implanted impurity profiles were studied after laser annealing in different regimes. It was found that the redistribution of impurities in silicon occurs after annealing with both millisecond and nanosecond laser pulses. The character of redistribution depends on the power density of the light beam. In the case of relatively low power-density the most probable mechanism of impurity migration seems to be interstitial diffusion. For high power-densities the redistribution is caused by the flux of excess vacancies or by the recrystallization of the melted surface layer.