Purpose: The aim of this study was to evaluate the pain sensation that orthodontic patients experience when initial arch wire is placed and to determine the degree of analgesic efficacy of low-level laser therapy (LLLT) comparing it with a placebo treatment using two different durations of laser application. Materials and Methods: This study was carried out as a randomized controlled clinical trial (split mouth design). The study sample consist of 20 patients (10 females, 10 males), between the ages of 15 and 25 years. Just before placing the initial NiTi wire a record of pain at time T1 had taken then the wire placed and fully engaged the bracket slot. The upper right side had irradiated using 910nm GaAlAs diode laser with an output power of 0.2W for 10s/point and of 2 j/point, three points were irradiated in the vestibular zone: two points at the third cervical (mesial and distal) and one in the apical third. After that three points were irradiated at the palatal zone in the experimental quadrant. The total energy released in all laser-treated teeth was 12 J. Irradiation was done for 1 min in group A(GA) and 1 min for 2 time in group B(GB) so that the output power (0.2w) and energy (2j/point) is fixed. The same procedure had repeated in the contralateral quadrant, but with laser switched off. This procedure was been done immediate after first wire insertion then it is repeated after 24 hours, 48 hours, and 72 hours. And results had taken using VAS scale before placing the wire and at 5min, 6h, 24h, 48h, 72h, one week, and two weeks after wire insertion. Results: Pain level reported for the experimental laser side was significantly less than that reported for the control placebo side (GA t= 0.56, GB t= 0.42) in both groups however the group B that exposed to laser more time show lower value of pain than group A. The mean pain value in laser exposed side more than that for placebo side for both groups. The progression of pain is the same for both groups. LLLT affect the level of pain but did not affect the onset of pain or the most painful day. GA showed more pain values than GB but there is no statistical or clinical difference during all the study time. Conclusion: the application of LLLT after the first wire insertion is an effective way to decrease orthodontic pain, but the increase of duration of LLLT has no obvious difference. Key words: LLLT, pain, orthodontic treatment.