The electroelastic interaction of a piezoelectric screw dislocation in the interphase layer with a circular inclusion and an unbounded matrix is dealt with. An efficient and concise method for complex multiply connected region is developed by combining the sectional holomorphic function, Schwartz symmetric principle, Cauchy-type integral and Laurent series expansion techniques, in terms of which explicit series form solutions of the complex potentials in the matrix., the interphase layer and the inclusion regions are derived. The image force acting on the piezoelectric screw dislocation is also calculated by using the generalized Peach-Koehler formula. The influence of the eletroelastic properties of the materials and the relative thickness of the interphase layer on the image force is discussed and shown in graphs. The results show that the above factors can drastically affect the motion of the dislocation in the interphase layer. In addition, a fundamental solution is provided in this paper to further investigate the problem involving interfacial defects and the dislocation mechanism. The present solutions contain a number of novel and previously known results which can be shown to be special cases. (c) 2006 Published by Elsevier B.V.