The feasibility of preparing large-particle-size monodisperse latexes in a simulated microgravity environment was investigated using a rotating cylinder reactor. A rotational speed of 8 rpm was chosen for the polymerization of polystyrene particles in the size range of 6-60 μm on the basis of results obtained in sedimentation studies. Improved particle-size uniformities were obtained when compared to more conventional polymerization techniques.