This article reports a photoreflectance study of the process‐induced strains in both dry etched CdTe/Cd0.875Mn0.125Te and GaAs/Al0.3Ga0.7As nanostructures patterned by electron beam lithography. The results show that compressive strains can be introduced in both the dry etched nanostructures and the layers underneath the etched surfaces due to the introduction of defect complexes and/or crystographic damage inflicted in the fabrication process. The effect of post dry etch thermal annealing on the strains in the dry etched nanostructures has also been studied. ©1995 American Institute of Physics.