Border molding is an important step in the fabrication of complete dentures. Conventional border molding using impression modeling plastic has been time-consuming and has resulted in a great variation in the shape of the recorded borders. This study compared the shape and variability of the vestibular impressions made with impression modeling plastic and a polyether impression material. Four prosthodontists each made five maxillary vestibular impressions using the two materials. All the impressions were made on one edentulous subject. The results showed significant differences at many locations along the border of the impressions. The borders of the impressions made with modeling plastic tended to be thicker and shorter than those made using polyether material. Use of the polyether material required less time to complete the border molding procedures and demonstrated a more consistent result in the shape of the vestibular impressions.