Strain relaxation commonly occurring in SiGe heteroepitaxial systems by misfit dislocations is a very important process affecting the properties of electronic and optoelectronic devices. Point defects introduced into epitaxially grown heterostructures can facilitate the strain relaxation and can even initiate the process themselves, without introducing misfit dislocations. In the present paper, an analysis of possible effects of point defects on the strain relaxation in epitaxial SiGe heterostructures is done. A phenomenological model of atomic rearrangement stimulated by point defects and resulting in the strain relaxation is proposed. Experimental data supporting the model are discussed. (c) 2005 Elsevier B.V. All rights reserved.