Objectives: purpose of this study was to assess the skeletal, dentoalveolar and dental changes produced by rapid maxillary expansion using the skeletal anchored hybrid hyrex expander with two different designs . subjects and methods: Twenty healthy patients with transverse maxillary deficiency based on the transvers analysis of Andrew's elements were selected. The patients were distributed in to two groups: group1: miniscrewes were placed perpendicular while group 2 were placed at lateral angulation. The CBCT images were performed before the start of the orthodontic expansion (T l) and 3 months after the last activation (T 2): the mean differences between pre-expansion and pos- expansion measurements within each group were measured. Results: pre and post expansion measurements did not differ statistically from one another. Skeletal expansion was observed in the clinical appearance of the midline diastema. Evidence of midpalatal suture opening with the hybrid hyrax expander was evident in the antero-posterior cephalometric radiographs. Hybrid hyrex has a clinical significance throughout increase most of maxillary arch parameters