Stafne's bone defect (SBD) is an uncommon bone alteration that affects the mandible and usually presents as an asymptomatic radiolucency located in the posterior region of body or angle of the mandible, below the alveolar canal. Although clinical and radiographic features are more often sufficient for the diagnosis, other lesions and bone alterations have been described in the differential diagnosis and may lead to a misinterpretation and an incorrect diagnosis. Herein, we report a case of an 89-yearold man with metastatic prostate cancer to multiple bones, presenting an asymptomatic solitary well-defined radiolucent image on the right side of the posterior body of the mandible, in close contact with its inferior border. A bone depression was confirmed by computed tomography scans of the mandible and a metastatic inclusion was ruled out by bone scintigraphy with a final diagnosis of SBD. The aim of this report was to highlight the importance of differentiating SBD from metastases in cancer patients and to reinforce the usefulness of multiple imaging modalities in the differential diagnosis of SBD. Key words:Stafne's bone defect, Mandible, Depression, Metastases, Imaging modalities.