The effect of low-frequency pulsed electromagnetic fields (PEMF) on bone was studied after an orthodontic treatment. A spring was positioned between the incisors and the first molar on both sides of the rabbit mandible for 14 days. A PEMF treatment was performed 6 h/day on the right side only. A greater distance between the first and the second molar was recorded in the PEMF treated side with respect to the left side. In addition, analysis of undecalcified sections shows a lower number and width of erosion cavities and a greater amount of newly formed (fluorescent) bone on the right side. In conclusion, PEMF treatment not only appears to increase bone formation, as previously reported in the literature, but, acting on osteoclast activity, also seems to improve bone quality during orthodontic treatment.