The effect of Si+implantation on the allowed and forbidden first‐order and on the resonantly excited second‐order Raman spectrum of GaAs has been studied. The implantation dose was varied between 5×1011and 1×1016ions/cm2. For doses exceeding 1015cm−2, the Raman spectrum of a completely amorphized surface layer was observed. In samples implanted with doses ≤1015cm−2, which show a partly crystalline/amorphous mixed state, the relative intensities of amorphous and crystalline features in the Raman spectrum vary significantly for different exciting photon energies. This is explained by differences in the dispersion of the Raman susceptibility in amorphous and crystalline GaAs. Dipole‐forbidden but defect‐induced first‐order scattering by longitudinal optical zone center [LO(&Ggr;)] phonons shows an initial increase with implantation dose, which is, for excitation resonant with theE1gap, followed by a saturation and even a decrease in intensity. This is understood in terms of an implantation‐induced broadening and lowering of theE1gap resonance in the Raman susceptibility which counteracts the increase in radiation defects. The intensity of resonantly excited 2LO(&Ggr;) phonon scattering shows a monotonic decrease with increasing dose, which also indicates a broadening of theE1gap resonance in the corresponding Raman susceptibility. These results demonstrate the sensitivity of resonant Raman scattering to radiation damage induced changes in the dielectric function and open the possibility for a sensitive assessment of implantation damage in GaAs.