Differential resistivity and Hall effect measurements and secondary ion mass spectrometry (SIMS) are used to study the annealing behavior of GaAs doped with high Be concentrations during growth by molecular beam epitaxy (MBE). The diffusion coefficient of MBE‐grown Be in GaAs is determined to be (0.5–1) ×10−13cm2/sec at 900 °C, a value which is two orders of magnitude lower than that for implanted Be of equal concentration [(2–3) ×1019cm−3]. The concentration dependence of the diffusion of MBE‐grown Be in GaAs is also observed to be substantially less than that for implanted Be. The implantation of He in Be‐doped MBE layers to create lattice damage does not significantly affect the Be diffusion in a subsequent anneal.