Abstract The 2D–3D growth mode transition of compressively strained In x Ga 1− x As layers ( x = 0.82 or 2% lattice mismatch) grown on an In 0.53Ga 0.47As buffer layer lattice matched to InP was studied using scanning tunneling microscopy. Up to 4 deposited monolayers, a layer by layer growth mode is maintained. The surface layer appears to be more compact for the strained layers than for the lattice matched buffer layer. After 5 monolayers were deposited the surface topography undergoes very significant change and threedimensional patterns, highly anisotropic in the growing plane, appear. These remarkable evolutions are attributed to the competition between surface energy necessary to form new island facets and elastic energy relaxation allowed with small sized islands.