A systematic review is conducted for adults with Obstructive Sleep Apnea treated with Rapid Maxillary Expansion. The objective was to evaluate the effects of various types of rapid maxillary expansion on the upper airway passage and which amongst the two types of RME is most effective in correction of OSA in adult patients. The data were obtained by clinical studies, we meant any study conducted with patients, either retrospective or prospective. The studies showing the outcomes of rapid maxillary expansion on obstructive sleep apnea in adults were included. The quality of each article was scored using an adapted version of 3 methods previously used by Fudalej and Antoszewska 25 Cozza et al26 and Chen et al27. PubMed, Google Scholar and Science Direct like databases were used for to extract various studies. From the available data, we can conclude that increase in the Nasal Width is seen more in Surgically Assisted Rapid Palatal Expansion than in Miniscrew Assisted Rapid Palatal Expansion. Change in Nasal volume/area is more evident in Miniscrew Asisted Rapid Palatal Expansion than in Surgically Assisted Rapid Palatal Expansion and similarly change in nasopharynx area is more pronounced in Miniscrew Assisted Rapid Palatal Expansion than in Surgically Assisted Rapid Palatal Expansion. Apnea Hypopnea Index (AHI) decreases in both the groups i.e. Miniscrew as well as Surgically Assisted Rapid Palatal Expansion in same amount inferring that there is improvement in breathing