To show the orthodontic treatment in a 8-year-old patient affected by Ectodermal Dysplasia (hypohidrotic type) and presenting multiple agenesiae, contraction of the maxilla and skeletal Class III malocclusion.Because of both oligodontia of primary and secondary dentition and no good retention and anchoring, a hybrid modified rapid palatal expander (RPE) was used. It presented dental anchoring with two bands on first upper molars and skeletal anchoring with two miniscrews in the anterior palate. The project included the use of a CBTC for the bone examination and precise silicon dental impression for the insertion of miniscrews.The procedure was successful and the patient solved the expansion in few days, so RPE has been embedded throughout 6 months in order to develop the bone at the median suture.This case report can be considered as a valid example for approaching patients affected by Ectodermal Dysplasia with multiple agenesiae and palatal contraction because of the difficult retention.