Pure motor monoplegia (PMM), characterized by motor involvement limited to one limb without sensory deficit, is a rare symptom in cerebrovascular diseases, brain tumor and brain abscess. Recently, we experienced two patients with small cortical infarction who presented with PMM : foot drop and distal weakness of upper extremity, respectively. In these cases, the lesions were not seen definitely by CT scan, but were detected by magnetic resonance imaging (MRI), which were restricted to the primary motor area in the opposite hemisphere. These cases illustrated that, though rare, infarction of cerebral cortex may cause pure motor monoparesis. We recommand MRI rather than CT scan in the evaluation of patients with sudden onset monoparesis.