We report on the effect of furnace annealing on 60‐A˚‐wide InxGa1−xAs/GaAs single quantum wells (SQWs) in the range of indium composition 0.1≤x≤0.5. Excitonic energy shifts of up to 120 meV were observed after annealing of the samples at 825 °C for 30 min. The fact that these energy shifts were strongly dependent of the indium composition in the well material was consistent with enhancement on the indium diffusion out of the wells associated with the presence of dislocations. The most dramatic changes, as a result of annealing, manifested by strain recovery were observed from the SQW withx=0.3 which as‐grown had a low dislocation density (quantum well thickness slightly exceeding the critical layer thickness for formation of dislocations).