Auto-transplantation is the repositioning of an autogenously erupted, partially erupted, or unerupted tooth from one site to another in the same individual. The purpose of this case report is to describe the auto-transplantation of the mandibular third molars as an alternative means of replacing second molars requiring extraction. An orthopantomogram revealed horizontal impaction of teeth #37 and 47 and mesio-angular impaction of teeth #38 and 48. Cone beam computed tomography revealed that the roots of #37 and 47 were in close proximity to the inferior alveolar canal bilaterally. As atraumatic and complete removal of these two teeth was not possible, #38 and 48 were chosen as the donor teeth instead. The procedure was carried out under general anesthesia. Teeth #38 and 48 were extracted atraumatically; teeth #37 and 47 were pulled out by sectioning and transplant sites prepared. Teeth #38 and 48 were transplanted to the sites vacated by teeth #37 and 47, respectively. Endodontic treatment of teeth #38 and 48 was completed within 1 month following transplantation. Both clinical and radiographic outcomes were considered satisfactory at 1 year postoperatively. Bone healing was observed around the roots of teeth #38 and 48. In conclusion, although auto-transplantation is not very common in general dental practice, we believe that it offers a clinically and economically viable alternative to other complicated prosthetic and dental implant treatments.