Pure monoparesis is a rare condition characterized by weakness limited to one limb without any other neurologic deficits. We herein report an extremely infrequent case of pure motor monoparesis not due to cortical infarctions but due to a paramedian pontine infarction. A 41-year-old woman was admitted with a sudden onset of weakness in her right upper extremity. On neurological examination, there were no abnormalities except for monoparesis (motor grade IV/V) in the right upper extremity. A magnetic resonance imaging of the brain showed an acute small ischemic lesion in the left paramedian pontine area.