The ability of dislocation patterns to control the lateral distribution of islands on the surface of strained heteroepitaxial systems is elucidated. We have studied the behaviour of Ge deposited on a Si surface modified by misfit dislocations generated in buried compositionally graded Si1-xGex layers. A pronounced ordering of the Ge islands on the dislocation-structured substrates is revealed, It is shown that this striking phenomenon is caused by the inhomogeneous surface-strain patterns associated with the misfit dislocations. The results open a new pathway to spatial manipulation of zero-dimensional structures in heteroepitaxial semiconductor systems.