The influence of maxillary advancement by osteotomy on speech was examined in 10 patients with cleft palates (6 males, 4 females). Ages at the time of surgery ranged from 16 to 26 years (mean, 19.5 yr). LeFort I and II osteotomies were performed in 9 patients and 1 patient, respectively. Preoperatively and postoperatively, hypernasality, nasal emission on pressure consonants, and articulation disturbances were evaluated perceptually, and velopharyngeal function was evaluated by lateral cephalographic and nasopharyngoscopic studies. Hypernasality, which had been judged preoperatively to be absent or slight in 1 patient each, remained unchanged after surgery, whereas the remaining 8 patients showed increased hypernasality after surgery. Nasal emission showed a similar tendency. Articulation errors were not improved postoperatively. Lateral cephalograms recorded from the patients with increased hypernasality showed increases in the shortest palatopharyngeal length and in the soft-palate-length--to--pharyngeal-depth ratio. Also, deterioration in velopharyngeal closure was noted postoperatively compared with preoperatively by nasopharyngoscopy in the majority of patients with increased hypernasality.