Purpose: This study was made to evaluate the level of receptor activator of nuclear factor- kappa B ligand (RANKL) in gingival crevicular fluid (GCF) and pain perception during orthodontic tooth treatment to evaluate the efficacy of low-level laser therapy (LLLT). Subjects and methods: A number of 10patients (age range: 15-20) requiring extraction of maxillary first premolars as a part of orthodontic therapy were selected randomly. A split-mouth technique was used. The test side received (LLLT) from a semiconductor (aluminium galliumarsenide) diode laser. The laser was irradiated on days 0, 2, 7, and14. The canine distalization was achieved with a force of 150 g per side using nickel titanium closed coil spring. GCF samples were collected from canines on days 0,7,14 and 30 using perio paper point #35. Enzyme-linked immunosorbent assay (ELISA) was used to assess levels of RANKL. Pain was assessed for one week from the intervention using a visual analogue scale(VAS).Gingival index and pocket depth were assessed at baseline and after 30 days. Results: There was no significant difference between RANKL concentrations in the two groups at base line, 7 and 14days. After 30 day; Laser side showed statistically significant lower mean RANKL (p=0.011) than control side. For pain: non significant difference was found between the two groups during the tested periods. Conclusion: LLLT showed no additional benefits over conventional canine retraction regarding pain and RANKL release. However,the laser group showed the least RANKL level at the end of the study which denotes biostimulatory effect of laser on bone cells.