Changes produced in the upper airway after rapid maxillary expansion makes this procedure a therapeutic option for treating sleep apnea-hypopnea syndrome (SAHS) in children. The objective of this systematic review and meta-analysis was to analyze the evidence available for the effects of rapid maxillary expansion (RME) on SAHS, analyzing changes produced in oximetric variables: apnea-hypopnea index (AHI); oxygen saturation (SO2); sleep efficiency (SE), total sleep time (TST), percentage of rapid eye movement (REM) phase; and arousal index (AI). An electronic search was conducted in the PubMed, Scopus, Embase, and Cochrane databases, and in grey literature (Opengrey). No limit was placed on publication date or language. Inclusion criteria were: patients in growth with sleep apnea who underwent rapid maxillary expansion with oximetric values registered before and after treatment. Articles with patient sample sizes <10 were excluded. Ten articles were included for qualitative synthesis and nine for meta-analysis (eliminating one observational study). AHI values underwent a mean reduction of 5.79 events/hour (CI -95% 9.06 to 2.5); an increase in mean oxygen saturation of 2.54 % (CI-95% -0.28 to 4.80, 6.7 %); a reduction in AI of 2.17 events/hour (CI-95% -5.25 to -0.582); an increase in REM phase of 1.20 % (CI-95% 1.02 to 1.38); and an increase in SE of 0.961% (CI-95% -1.574 to 3.495). RME would appear efficient for treating slight or moderate SAHS, as indicated by improvement in oximetric parameters; it may be effective as coadjuvant therapy to adenotonsillectomy in severe cases of children with maxillary compression.