Aim: This review aims to evaluate the long-term effects of rapid palatal expansion (RPE) on the pharyngeal airway and nasal cavity using three-dimensional (3D) analysis. Background: Skeletal maxillary transverse deficiency is known to be an anatomic etiological factor for developing sleep-disordered breathing in growing patients. Also, rapid palatal expanders have been used for over a century for bringing transverse skeletal expansion, but their long-term stability on the nasal cavity and pharyngeal airway remains questionable. Results: Electronic search of different databases as well as manual search from inception to December 2020 yielded 529 articles. The search included a combination of the following keywords like “rapid maxillary expansion (RME),” “pharyngeal airway,” “nasal cavity,” and “3D evaluation.” To evaluate the long-term effect of RPE, studies with minimum retention of 6 months postexpansion were only included. After screening and selection based on Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, nine studies were included for the final qualitative analysis. ROBINS-I tool was used to assess the risk of bias in the included studies. Meta-analysis was not performed due to heterogeneity between studies. Conclusion: The existing evidence shows that in growing children, RPE expands nasal cavity volume, improving nasal breathing, and the results are stable. However, long-term stability on increasing pharyngeal airway volume could not be sustained. Clinical significance: The evidence seems to support RPE can be a useful method for increasing the nasal cavity volume in the long-term and appears to have a clinically similar long-term effect on the pharyngeal airway as the control group. Thus, RPE can be considered an effective method for the management of pediatric obstructive sleep apnea.