Magnetic resonance imaging (MRI) offers a sensitive alternative to computed tomography (CT) for lesion localization. Patients with subacute necrotizing encephalomyelopathy (SNE) may be diagnosed by finding focal lesions on CT that correspond to sites of anatomical involvement. We report serial CT and MRI scanning findings in a patient with clinical, radiographic, and laboratory evidence of SNE. MRI was more sensitive in detecting lesions involving the basal ganglia, brainstem, and cortex. We believe MRI is a valuable and sensitive means to establish an antemortem diagnosis of SNE.