Metallic parts made by Selective Laser Melting (SLM) are known for their heterogeneous microstructures in the as-built (AB) state. In this paper, Laser Shock Peening (ISP) was performed on a 316 L stainless steel part fabricated by SLM. The LSP treatment increases the stored energy in the material but does not lead to measurable grain refinement. When subsequently annealed, the LSP treated sample undergoes recrystallization and transforms into a refined equiaxed structure, while this transformation is not activated yet for the AB sample. The ISP strategy therefore offers new routes for the selective 3D control of microstructures and mechanical properties of SLM parts.