Six patients with a clinical diagnosis of lateral medullary infarction have been studied by CT scan and Magnetic Resonance Imaging (MRI). The MRI study was performed on a CGR Magniscan 5000 with a superconducting magnet of 5 Tesla. In all patients T2 weighted images (TR = 2000, TE 60, 120) in joined section of 9 or 6 mm thickness were obtained in the axial plane. Three patients were also studied in T1 weighted sequences (TR = 500, TE = 28). A lateral medullary infarct was shown in 5 patients. MRI findings were consistent with a hemorrhagic infarct in one case. Occlusion of a vertebral artery was suggested in 2 cases and was confirmed by angiography. In 3 cases, an associated ipsilateral cerebellar infarct was demonstrated. The CT scan had only shown bleeding in the medulla oblongata in the hemorrhagic infarction case, and a cerebellar infarction in another case. Some clinical manifestations are discussed with regard to the results of MRI. MRI appears as the best current method to improve clinico-topographic correlations in medullary infarcts.