The aim of this study was to examine changes in nasal resistance longitudinally from age 9 to 13. The study population consisted of 82 children whose nasal resistance was measured annually. The results showed that as nasal resistance significantly decreased with age, it also increased transiently at some point between ages 9 and 13, The timing of the transient change in resistance varied among individuals, but it usually occurred before age 12. No gender differences were observed,The results suggest that clinical signs of nasal impairment may periodically occur and then disappear in prepubertal orthodontic patients.