Materials with an average particle size of less than about 50 nm often show new or at least enhanced physical properties. In many cases nanocrystalline ionic conductors exhibit a high increase of cation, e. g. Li+, or anion, e. g. F−, diffusivity. In the present contribution we review recent studies on ion dynamics in nanocrystalline ion conductors, both single-phase systems and composites, being prepared by high-energy ball milling. These include, e.g., LiTaO3, Li2O:Al2O3, LiF:Al2O3, BaF2, CaF2, BaF2:CaF2 and (BaF2:CaF2):Al2O3. Dynamic properties were probed by 7Li and/or 19F NMR line shape and relaxation as well as ion conductivity measurements.