Orthodontic treatment has two major problems: being lengthy and costly procedure. The present study was designed to evaluate the clinical efficacy of locally injected vitamin D3 Keywords: Orthodontic, Calcitriol, Local injection, OTM (calcitriol) in accelerating orthodontic teeth movement (OTM) and reducing treatment time and cost in humans. The study was performed on 15 Iraqi adult orthodontic patients within the age range 17-28 years, they are randomly allocated into three groups, each of five patients and treated with either 15 pg, 25 pg, or 40 pg/0.2ml calcitriol diluted with 10% dimethylsulfoxide (DMSO). The maxillary arch of every patient was divided into control (right) and experimental (left) sides. In addition to force application, the right canine received 0.2 ml DMSO injections while the left canine received the calcitriol injections. The follow up period for every patient included five visits at one week intervals through which they received two injections three times and evaluated for OTM, GCf collection and radiographic examination. Statistically nonsignificant differences were reported for OTM between control and experimental sides, and among the three groups. However, on clinical efficacy basis, the dose of 25 pg calcitriol produced about 51% faster rate of experimental canine movement compared to control, while each of the 15 pg and 40 pg doses resulted in about 10% accelerated OTM. Further more, the periapical radiographs showed no any damaging effect of calcitriol to the surrounding tissues. In conclusion, for the first time we reported that locally injected calcitriol, in dose dependent pattern, is clinical and cost effective in humans.