The patient, a 32-year-old man, presented with sudden onset of occipital headache, vertigo, dysarthria, gait ataxia, right Horner syndrome, numbness of the right hand, and mild right hemiparesis. On magnetic resonance imaging, an acute small infarction was located on the right side of the caudal medulla extending dorsomedially. Magnetic resonance angiography showed severe right vertebral artery stenosis. Lateral medullary infarction associated with ipsilateral sensorimotor deficits in the limb is very rare, and the lesion probably involved the ipsilateral dorsal column or decussating lemniscal fibers and corticospinal fibers caudal to the pyramidal decussation or compression of the decussation.