PTFE (polytetrafluoroethylene) membrane filters were tested for preparing corn oil emulsions by the membrane emulsification method using a pre-emulsified emulsion. A hydrophilic PTFE membrane was used to prepare an O/W emulsion without any disturbance of the continuous phase. A W/O emulsion was prepared with a hydrophobic membrane filter in the same way. The higher the flux of the pre-emulsified large particle emulsion via the membrane was, the higher the monodispersibility of the membrane emulsified emulsion became. There was no limit to the emulsifying pressure or the emulsifying rate under the conditions tested. The mean particle diameters of the O/W and W/O emulsions were ca. 3 times the mean pore size of the membrane used.