Monodisperse poly(methyl methacrylate) (PMMA) particles in the size range of 1-5 mu m were prepared by unseeded dispersion polymerization in methanol-water media using ate-type initiator and poly(acrylic acid) (PAA) or poly(vinyl pyrrolidone) (PVP) as a steric dispersant. The influences of various polymerization parameters, such as polymerization temperature and time, concentration and type of initiator, concentration, type and molecular weight of dispersant, composition of the reaction media including dispersed medium and monomer, content of electrolyte and crosslinking agent on the particle size and particle size distribution were systematically investigated.