Abstract : The aim of this study was to evaluate the effect of low-level laser irradiation in accelerating tooth movement along with self-ligating brackets in dento-alveolar posterior bilateral cross bite correction in adults. Thirty one patients (mean age: 18-25 years) with bilateral posterior crossbite of dento-alveolar origin, Split mouth design was performed and followed, Each upper arch was divided into two sides (experimental and control). Separation rubber was applied for a week then attach the orthodontic brackets and bands and 0.013-in archwire was applied. The laser was applied to the experimental side with a wavelength of 830 nm in a continuous mode (energy density, 1 J/cm2) on 3 points buccally and palatally around each root of upper first and second premolar and upper first molar on the experimental side; the other side was designated as the control with nontherapeutic light applied. Laser irradiation was applied at baseline and then on the 3rd, 7th, 14th, 21th day after that repeated every mouth until the crossbite corrected. A CBCT image of the upper jaw was taken after the two ends came out of the dental alveolar crossbite to assess the changes in the thickness of vestibular alveolar bone and degree of torque on upper first molar and first, second premolar before and after treatment on both sides. The thickness of vestibular alveolar bone on upper first and second premolar and first molar before the treatment was significantly different after treatment on both the experimental and control sides (p<0.05), the same was for the degree of torque on upper first and second premolar and first molar on both sides. The thickness of vestibular alveolar bone and degree of torque on upper first and second premolar and first molar was nonsignificant (p > 0.05) between the two sides before and after treatment. Within the limitation of this study we can conclude that the laser did not have an additional role in increasing treatment efficacy and the self-ligating brackets were effective in correcting posterior crossbite by widening the upper arch.