Nanosize poly(methyl methacrylate) (PMMA) microlatexes with high PMMA/surfactant ratio have been successfully prepared by a modified microemulsion polymerization, i.e., continuous and slow addition of monomer (MMA) to the polymerizing MMA microemulsion with mild stirring. Number-average diameters of 33-46 nm with narrow polydispersity (D-v/D-n = 1.1) and polymer content of 6-24 wt% were achieved using low levels of surfactant (dodecyltrimethylammonium bromide, DTAB)-less than 1 wt% of the reaction mixture. Particle diameter depended on polymerization temperature, MMA content, and concentrations of initiator and surfactant. Larger particles were formed when temperature was too high, initiator concentration was too high, or surfactant concentration was too low.