With the development of electrophysiologic technique, a more detailed topographical organizations of motor cortex, especially hand area have been introduced in animal experiment. To the best our knowledge, in cerebral infarction, only one patient with isolated weakness of intrinsic hand muscles has been reported. We present two patients with cerebral infarction who showed isolated weakness in their intrinsic hand. Patient 1; A 76-year-old woman with coronary artery obstructive disease developed abrupt weakness in flexion of right thumb, index, middle finger and in adduction of thumb. Brain MRI showed a small discrete lesion in the posterior bank of left precentral gyrus. An angioraphy revealed an occlusion of left central sulcus artery. Prominent thumb adduction weakness was remained 11 days later. Patient 2; A57-year-old hypertensive man was admitted because of recurrent TIA and decreased grasp power of right hand, especially flexion and adduction of thumb, index finger and middle finger. Brain MRI showed focal lamina necrosis in left precentral gyrus. An angiography revealed and occlusion of left internal caroid artery. Findings in our patients suggest that the similar arrangement of afferent zone for cortical hand area found in monkeys also may exist in human beings.