Over the last decade, the use of polycaprolactone has attracted much interest in drug delivery compared to biodegradable polyesters derived from lactic and glycolic acids. The methodologies commonly used for the preparation of polycaprolactone microparticles are associated with many problems regarding the control of particle size and size distribution and particles morphology. Membrane emulsification/solvent diffusion processes offer great potentials in manufacturing particles. In this work, polycaprolactone microparticles with mean diameter of 20 mu m, spherical shape and smooth surface have been successfully produced using the emulsification/solvent diffusion method. The fluid-dynamic and chemical parameters have been optimized to produce uniform particles with a span value of 0.5. The effect of process parameters controlling the solvent diffusion on the shape and surface morphology has also been investigated. The use of microporous membranes allowed the simultaneous particle size and size distribution control during the emulsification step. Also, the solvent diffusion permitted easy control of the size and morphology of particles during the solidification of polymer within the droplets. (C) 2014 Elsevier B.V. All rights reserved.