Background: Orthodontic extraction protocol induces a lot of modification in oral cavity. Searching the current orthodontic literature resulted in controversial opposing results regarding the effect of orthodontic extraction on the pharyngeal spaces, so the question remains unanswered.Null Hypothesis :The null hypothesis states that there is no difference in the quantitative effect on pharyngeal airway dimension of adult orthodontic patients treated with extraction treatment protocol.Objective: To perform a systematic review based on a PIO question to quantify the amount of changes in the pharyngeal spaces or ; hyoid bone and tongue position that maybe resulted from orthodontic extraction in adult patient. Search Strategy : Electronic databases were searched up to December, 2014 in (CENTRALCochrane register of controlled trials, PubMed, CNKI,Wangfangdata,Scielio and LILACS). Grey literature was also searched electronically through Google Scholar, central library in Cairo University and the Cairo Dental Journal (CDJ) as well as high impact factor journals in the field (AJODO, and The Angle Orthodontist). Citations of all the included studies were also checked manually for relevant articles. During the search language restriction was not applied.