In this paper we establish a generalized Wulf-Kaishew theorem giving the equilibrium shape of a 3D crystal A deposited coherently onto a lattice mismatched planar substrate B. Our mains results are: (1) The epitaxial strain acts against wetting so that globally it leads to a thickening of the equilibrium shape. (2) Owing to the coherent strain the equilibrium shape changes with size. More precisely the various facet extensions change during the growth, some facets decreasing, some others increasing. (3) Each dislocation entrance, necessary for relaxing too large crystals having thus stored a prohibitive elastic energy, modifies abruptly the equilibrium shape and thus the different facet extension. Some experimental evidences are discussed.