The authors describe the case of a 3-year-old boy who presented with a mobile right maxillary primary canine. Clinical examination revealed this tooth to have an abnormally large crown, which appeared to have sustained a crown-root fracture. Periodontal probing depths of 5 mm were detected around the tooth. Radiographically, there was a marked constriction at the cementoenamel junction with associated alveolar rarefaction. Both upper primary canines were subsequently removed under general anaesthetic and the right canine was subject to histopathological investigation. A diagnosis of external cervical resorption was made. A review of the literature confirmed this to be a very unusual case presentation.