A retrospective study was undertaken to compare the accuracy of internal vs external reference points when repositioning the maxillary central incisor during maxillary surgery. Seventy-eight patients who underwent Le Fort I osteotomies (with or without concomitant mandibular surgery) were used in this study. For 37 patients, caliper measurements were taken between one bur hole along the pyrifornm aperture and another in the mobilized segment ( internal reference point ) for determining the vertical dimension; in the remaining 41 patients, measures were taken between the orthodontic bracket and a mark on the root of the nose ( external reference point ). Standardized preoperative and immediate postoperative lateral cephalograms were traced and digitized. The surgical change in the vertical and horizontal position of the maxillary incisor was calculated using Frankfort horizontal as the reference plane. The actual change was then compared to the predicted change (determined from results of model surgery) using the Student + test. The results showed the external reference point to be a more reliable method of positioning the maxilla in the vertical dimension (P < .001) than the internal reference point. However, there was no significant difference between the results obtained using an internal vs external reference point when the horizontal position of the maxillary incisor was evaluated and compared to the rpedicted change. This study indicates that the use of an external reference point can improve the predictability of vertical maxillary surgical repositioning.