A case of ameloblastoma is reported, which resembles both clinical and radiological presentation of brown tumours of hyperparathyroidism in the mandible. A 70-yearold man was treated for a mass in the lower jaw. Some laboratorial exams confused the authors regarding ameloblastoma and brown tumour from hyperparathyroidism. Ameloblastoma is regarded as the most usual odontogenic tumour. It is a benign tumour of the enamel organ without enamel formation. This tumour generally occurs in the middle-age group with the highest frequency observed at 33 years of age. Ameloblastoma occurs in all areas of jaws, but the lower jaw is most frequently affected. Within the mandible, the molar angle ramus area is affected three times more often than the premolar and anterior regions combined. Laboratory and radiological examinations were fundamental in establishing the final diagnosis. To the authors’ knowledge, this case was the second unconventional case of benign ameloblastoma associated with hypercalcemia reported in the literature.