Plasma electrolytic polishing (PEP) has proven to be an effective surface finishing technique for complex additively manufactured (AM) components due to its ability to process intricate geometries. This capability makes PEP particularly suitable for lattice structures, which are widely used in aerospace and biomedical applications due to their favourable strength-to-weight ratio. However, ensuring uniform polishing of both the outer and inner surfaces, especially for high-density lattices, remains a challenge. In this study, SS316L lattice structures with different cell sizes, which affect their overall density, were polished with PEP under two conditions: with and without forced electrolyte flow. An external nozzle system was used to direct the forced flow and enhance electrolyte penetration into the inner regions of the lattice structures.