Hemispatial neglect is a kind of cognitive impairment characterized by failure to report,respond or orient to stimuli presented in ipsi-or contra-lateral space after brain injury,which cannot be attributed to sensory or motor defects.Although there are various diagnosis and assessment methods,none is regarded as standard.The paper and pencil test is commonly used in routine clinical workup.The mechanism is controversial and the most accepted opinion is due to visuospatial attention defect.Imaging study focuses on exploring the functional regions leading to the hemispatial neglect.As functional imaging,SPECT and PET have capability to evaluate the perfusion,glucose metabolism and cellular vitality,which have been found increasingly useful and applicable clinically in the field of diagnosis for cognitive impairment diseases.They are likely to have potential for contribution in the study of hemispatial neglect.