The aim of this paper was to determine the prevalence of malocclusions in 12-year-old schoolchildren from Cuenca, Ecuador. A cross-sectional study was carried out, including a clinical examination of 181 schoolchildren aged 12 years, who were randomly selected from the schoolchildren population. We assessed the presence of malocclusions using the Angles classification. The analysis was performed in the program EpiInfo 7.2. The majority of the patients presented malocclusions (91.7%). There is no significant difference between public and private schools and the male sex was slightly more affected. There was a predominance of the Class II division 1 (30.4%), followed by Class III (25.4%), and Class I (24.9%), with the lowest prevalence reported for Class II division 2 (11%). A high rate of malocclusion was found in in 12-year-old schoolchildren from Cuenca, Ecuador, in both males and females. The dominant malocclusion in this study was Class II division 1.