Using a novel microchannel (MC) emulsification method, we are able to form microspheres (MS) with narrow size distributions. MC emulsification and subsequent solvent evaporation were performed to prepare micron-scale lipid MS with relatively narrow size distributious. The experimental systems with hexane as the dispersed-phase solvent stably formed oil-id-water (O/W)-MS with average diameters of 10-11 mum and coefficients of variation below 8% from the uniformly sized channels. The sodium dodecyl sulfate- and pentaglycerol monolaurate-containing systems performed the successful MC emulsification. Lipid MS with average diameters of 1-3 mum and coefficients of variation of about 20% were obtained through successive solvent evaporation of the formed monodisperse O/W-MS composed of 0.1-1.0 vol% tripalmitin in hexane. The diameters of the resultant lipid MS corresponded well to their estimated diameters, regardless of the tripalmitin concentration.