Root resorption is a common but undesirable side-effect of orthodontic treatment. It is a well-recognised phenomenon largely associated with impacted or unerupted teeth and in most cases, is mild and does not affect longevity of the affected teeth. This case report of a medically fit and healthy Caucasian boy who was undergoing orthodontic treatment at the Eastman Dental Hospital, UCLH (EDH) for management of his severe hypodontia, presents an unusual incident of bilateral resorption of his maxillary first permanent molars by the unerupted second molars. The near end-of treatment radiographs showed that both upper second molars were mesio-angularly impacted and resorbing the first molars; however, the patient reported no associated signs or symptoms. Bilateral Cone Beam Computed Tomography radiographs were requested for the posterior maxillary arch in the area of the molar dentitions and extensive root resorption affecting the first molars caused by the crown of the mesio-angularly impacted second molars was evident. This unusual bilateral root resorption of maxillary first molars associated with unerupted second molars is an uncommon presentation, with no similar case reports found in the literature. Great emphasis should be placed on informed valid consent and potentially making the patient aware of the small but potential risk of resorption of erupted terminal molars where orthodontic molar distalisation is considered.