A photoionization experiment on free oriented molecules in the gas phase has been performed. CH3I molecules in a supersonic beam have been oriented with respect to the molecular axis parallel to an external field by use of an electric hexapole. The photoelectrons ejected by vacuum ultraviolet radiation in a region of a very weak field from the lone-pair orbital located at the iodine atom show a pronounced asymmetry depending on whether electrons are emitted parallel or antiparallel to the molecular axis.