The purpose of this study was to evaluate the effect of surgically assisted rapid maxillary expansion on the sagittal and vertical maxillary planes. Thirty-three adult patients aged between 18 and 40 years who required surgically assisted rapid maxillary expansion were included in this study. They were divided into two groups: the Haas type expander (16) and the Hyrax type expander (17). All patients were subjected to subtotal LeFort I osteotomy with pterygomaxillary disjunction. Lateral cephalometric radiographs were taken during the preoperative assessment (T1), soon after completion of the expansion (T2), and 4 months after the end of the expansion (T3). The following cephalometric measures were obtained in each of the three radiographs for all the patients: SNA, SN palatal plane, Frankfurt horizontal plane. NA, CF-A, CF-NA, Nperp-A, CF-A, Frankfurt horizontal plane-ANS, and Frankfurt horizontal plane-PNS. Statistically significant changes were observed in the cephalometric measures: SNA, Frankfurt horizontal plane, NA, Nperp-A in the patients in the Haas group, and CF-A in the patients in the Hyrax group, demonstrating anterior displacement of the maxilla. The cephalometric measures SN. palatal plane, CF-A, CF-NA, Frankfurt horizontal plane-ANS, and Frankfurt-PNS plane that evaluated vertical displacement did not show changes in either group. The surgically assisted rapid maxillary expansion caused anterior displacement of the maxilla in both groups, but only the Haas group had statistical significance. Neither the Haas group nor the Hyrax group showed vertical displacement of the maxilla. When Hyrax and Haas groups were compared, there were no statistically significant differences for sagittal and vertical changes.