The temperature rise in an ion‐implanted silicon sample illuminated by a pulsed laser (ruby or Nd : YAG) is determined by numerical solution of the heat‐diffusion equation. The temperature dependence of the thermal conductivity and the free‐carrier absorption are included in the calculations. The latter was found to have a very significant effect when the laser is operated in theQ‐switched mode. The analysis shows that annealing in this mode almost certainly involves melting of the sample surface. In the free‐oscillation mode, however, free‐carrier absorption is negligible, and this mode may therefore provide a method of melt‐free annealing.