OBJECTIVES: The solid/multicystic ameloblastoma is a slowly growing, locally invasive epithelial odontogenic tumour. In 80% of cases this lesion occurs in the mandible, mainly in the posterior region, and it is characterized by the involvement of the inferior alveolar nerve. A panoramic radiograph of a 43-year-old man with chronic deep pain in the posterior area of the mandible showed a multilocular radiolucent lesion with scalloped borders in the left mandibular ramus. After the execution of a computed tomography of the jaws, to accurately determine the limits of the lesion and the relationship with the the inferior alveolar nerve, the magnetic resonance imaging was used. METHODS: The spatial relationship between the lesion and the inferior alveolar nerve was defined comparing different imaging methods: panoramic radiography, computed tomography and magnetic resonance imaging. T1-weighted fast spoiled gradient-recalled echo, T1-weighted fast imaging employing steady-state acquisition, T2-weighted interactive decomposition of water and fat with echo asymmetry least-squares estimation and Diffusion weighted imaging acquisition sequences were used on a 3.0 T unit. RESULTS: Regarding the inferior alveolar nerve course and its spatial relationship with the mandibular lesion, magnetic resonance imaging provided more detailed spatial and structural information than other imaging methods. CONCLUSION: The described acquisition sequences allowed us to highlight the diagnostic efficacy of the magnetic resonance in the morpho-structural characterization of a maxillofacial lesion and showed the importance of this imaging method as an additional technique to the computerized tomography in the maxillofacial surgical planning, resulting in a risk reduction of the inferior alveolar nerve surgical injury.