The purpose of this study was to investigate the predictability of using the inferior medial canthus as a stable external reference point for establishment of the vertical dimension in maxillary orthognathic surgery. Ten consecutive patients with skeletal Class II malocclusion and open bite who underwent orthognathic reconstructive surgery were included in the study. Prediction tracings were completed preoperatively and superimposed on an immediate postoperative lateral cephalometric radiograph. In 7 patients, the vertical positioning of the maxillary incisal edge on the immediate postoperative lateral cephalometric radiograph showed no difference from the superimposed preoperative prediction tracing. One patient showed 1 mm difference and 2 patients showed 2 mm difference from the preoperative prediction tracings. All cases resulted in acceptable maxillary incisal exposure relative to upper lip stomion. It is concluded that the inferior medial canthus can be used as a reproducible external vertical reference for orthognathic surgery when the technique described herein is used.