Multihollow-structured poly(methyl methacrylate) (PMMA) particles were produced employing the water in oil in water (W/O/W) emulsion polymerization technique where sorbitan monooleate was used as a primary surfactant and sodium laurylsulfate and Glucopen, a polypeptide derivative, were used as secondary surfactants. Vinyl acetate was copolymerized to improve the wettability of the particles. The agitation speed and concentration of the urethane acrylate employed as a reactive viscosity enhancer played a crucial role in determining the morphology and average size of the PMMA multihollow particles. Ln high agitation speed the multihollow particles displayed a small size and narrow size distribution resulting from efficient droplet breakup. Especially when the urethane acrylate was incorporated, PMMA multihollow particles with a smooth and clear surface were achieved. This was believed to be because the urethane acrylate increased the viscosity of the monomer mixture and helped to form the stable W/O/W emulsion droplets that restricted droplet coalescence during polymerization. (C) 2000 John Wiley & Sons, Inc.