At present, the high-energy milling method becomes widely used for the preparation of nanocrystalline materials due to its relative simplicity and availability. In this overview, selected examples are presented of the preparation of nanoscale materials by homogeneous and heterogeneous mechanochemical reactions in spinel ferrites. Despite numerous efforts, the understanding of the nonequilibrium mechanochemical processes is considered to be far from complete, leaving large scope for further research in this exciting field.