Some renarks about the mechanism for dynamic annealing during high dose rate P implantation of Si are reported. TEM observations and RBS channeling measurements show that the ion bombardment enhances the amorphous to crystalline transformation in the temperature range 200 ≤ T ≤ 600°C. It is found that the ratio between the observed recrystalli-zation velocity and the thermal SPE velocity decreases with increasing temperature. This indicates that a transition temperature must exist between the ion-assisted recrystallization regime and the ?lermal SPE regime. For the energy (100 keV) and the dose rate (60,uA/cm2) used in our experiments the transition temperature is about 700°C.