The aim of this study was to evaluate the long-term effects of semirapid maxillary expansion (SRME) and mandibular symphyseal distraction osteogenesis (MSDO) on dentofacial structures in adult patients. The sample comprised posteroanterior cephalograms of 14 patients, with an age range between 15.8 and 25.01 years (mean, 20.09 ± 2.36 years) at the start of treatment. Records were obtained before treatment (T1, day 0), at the end of SRME and MSDO retention (T2, 4.57 ± 0.65 months), at the end of orthodontic treatment (T3, 22.14 ± 4.69 months between the end of SMRE/MSDO retention of SRME/MSDO and end of orthodontic treatment), and after a 5-year follow-up period (T4, 4.99 ± 1.00 years, between the end of orthodontic treatment and follow-up). Data were analyzed statistically by using the repeated measure analysis of variance and paired t test. Statistically significant changes were observed in the lower nasal, bimaxillary, upper molar, upper incisors, lower molar, and lower incisors at the end of the retention period ( P