This paper presents a novel and facile route to preparation of highly uniform polymeric microspheres through a quiescent polymerization with the reactor standing still without any stirring. Using one single monomer, isophorone diisocyanate (IPDI), highly uniform polyurea microspheres are achieved with high yield via precipitation polymerization of IPDI with water in water-acetone mixed solvent. Full conversion of IPDI to polymer is readily achieved thanks to the step polymerization mechanism involved. The monomer concentration can go up to 11 wt.% with the polymerization accomplished within 2 h, with a much higher yield of microspheres in a much shorter time than those reported with vinyl monomers. The size of the microspheres is adjustable by changing IPDI concentration, acetone/H2O ratio in the solvent or polymerization temperature. Without need of any stirring or shaking during the polymerization, the protocol renders the fabrication of uniform microspheres more practical and economical, particularly for large scaled production. (C) 2012 Elsevier B.V. All rights reserved.