Mouth breathing in childhood can compromise the dental occlusion and, consequently, the functions performed by the stomatognathic system. The purpose of this systematic review was to evaluate which is the highest prevalence of dental malocclusion in mouth breathing children. Bibliographic searches of observational studies were performed in five electronic databases (PubMed, LILACS, SciELO, Scopus and Open Grey) without language restriction, from 2007 to 2014. Were selected cross-sectional or longitudinal studies of the past seven years that described the prevalence of malocclusions of Angle Class I and Class II, division 1. After the selection, the studies were evaluated for their methodological quality. Subsequently, the description of the selected articles was made. From 125 records, seven articles were selected (5.6%), with a majority of Brazilian authors (71.43%). There seems to be a higher prevalence of malocclusion in mouth breathers when related to gender. The prevalence of malocclusion of Angle Class II, division 1, was higher than Class I malocclusion in mouth breathers, according to most studies in the sample. Interdisciplinary and controlled studies deserve more attention from researchers of the area, given the need for researches with greater methodological strength. Considering the results, the prevalence of malocclusion of Angle Class II, division 1 tends to be higher than Class I malocclusion in mouth breathing children.