Pure motor hemiplegia (PMH) is, in most cases, caused by a lacunar infarction. However, pure motor monoparesis (PMM), i.e., isolated motor involvement with spasticity in one limb, has drawn little attention. We studied prospectively 5 patients with PMM and found that it was always due to a mass lesion in the contralateral superficial cerebral hemisphere. Our observation suggests that PMM should not be regarded as simply a variant of PMH.