introduction: by clinical definition, mouth breathers use the mouth as their main air pathway during breathing. this results in modifications to tongue and head positioning and may have an influence on craniofacial mechanics during development. bringing the head forward is also common among mouth breathers and may lead to misalignments in adjacent segments of the human body. objective: to evaluate neck (cervical) range of motion (rom) among mouth-breathing children and compare this with a group of nose-breathing children. method: ten mouth-breathing children of both sexes aged 6.90 ± 1.37 years and ten nose-breathing children aged 7.70 ± 1.42 years participated in this study. the rom for neck flexion, extension and protrusion of the head were evaluated. student's t test for independent samples was used for the statistical analysis, considering p< 0.05 as the statistical significance level. results: the mouth-breathing children had a significantly smaller rom for neck extension (59.0o ± 10.79o), compared with the nose-breathing group (72.9o ± 8.82o ) (p= 0.001). the rom for flexion and protrusion was not statistically different between groups (59.0o ± 10.79o). conclusion: the mouth-breathing children presented smaller neck extension rom than the nose-breathing children did, but for protrusion and flexion rom there was no difference between the groups.