Extended x‐ray‐absorption fine‐structure measurements have been performed at the AsKedge of GaAs/InP and InAs/InP strained single heterostructures grown by molecular‐beam epitaxy. The results show a substantial conservation of the bond length in the strained epitaxial layers with respect to the corresponding bulk materials. The measures point out the formation of a thick InAsP (or InGaAsP) layer at the GaAs/InP interface. ©1995 American Institute of Physics.