Methods for preparing zeolites with the particle size of 50–200 nm usingmechanical milling on bead mills (top-down approach) are analyzed. The millingcan be described by a first-order rate equation, but mathematical modelsallowing prediction of the particle size and degree of crystallinity of zeoliteafter milling, based on the process parameters, are still lacking. The millingis accompanied by degradation of the zeolite lattice, leading to a decrease inthe zeolite crystallinity and activity in catalytic reactions. Recrystallizationand dealumination may be promising ways to restore the zeolite structure aftermilling; in this case, the choice of the conditions for such posttreatment is ofcrucial importance. Evolution of textural and acid properties of zeolites in thecourse of milling is considered, and the effect of milling conditions on thecatalytic activity of zeolites in various reactions is discussed. The mainoutcome from a decrease in the size of zeolite catalysts is an increase in theiractivity and a decrease in the deactivation rate.