A novel method for continuous production of monodispersed oil-in-water (O/W) emulsion is developed using a crossflow-type silicon microchannel plate. On the single crystal silicon plate, a liquid flow path for continuous phase was made, acid at each side of the wall of the path an array of regular-sized slits was precisely fabricated. A flat glass plate was tightly attached on the microchannel plate to cover the top of the slits to form the array of microchannels, Regular-sized oil (triolein) droplets were generated by squeezing the oil through the microchannels into the continuous-phase water (0.3 wt% sodium lauryl sulfate solution) flowing in the liquid path. Oil droplet size is significantly dependent on the microchannel structure, which is identified with the microchannel width, height, and the length of the terrace (a flat area at the microchannel outlet). Three types of microchannel plates having different microchannel structures generate monodispersed emulsions of different average droplet sizes, 16, 20, and 48 mu m at the water flow rate of 1.4 x 10(-2) mL.min(-1). For the microchannel plate which generates large droplets of 48 mu m, increasing the flow rate causes decreasing droplet size. However, for the microchannel plate which generates small droplets of 16 or 20 mu m, the size is not affected by the flow rate within the range from 1.4 x 10(-2) to 2.4 mL.min(-1). In every case, the droplet size distribution is narrow, and the geometric standard deviation is 1.03 or less.