We present the case of a young man who experienced a sudden onset of pure motor hemiplegia in association with ulcerative colitis. Based on a review of earlier reports, ulcerative colitis was suspected to be the background disease leading to cerebral infarction. A cerebral infarction of the lacunar type in the right ventromedial aspect of the upper pons was seen on magnetic resonance images. These images detected small lesions in the brain stem, and were used to follow-up their transitions.