We interpret published depth profiles of deuterium inn‐ andp‐type GaAs, following long anneals at 500 °C in a gaseous deuterium atmosphere, as indicating the indiffusion of a native defect (probably VAs) and an impurity (possibly O), both tagged with deuterium. Model fits yield the 500 °C diffusivity of the tagged impurity as 4×10−14cm2/s and the diffusivities of the tagged native defect as 3×10−15cm2/s inn‐GaAs and ∼8×10−15cm2/s inp‐GaAs.