The authors describe the diaschisis phenomenon-its history, the present state of art and its types, in particular crossed cerebellar diaschisis. We report its diagnosis, occurrence, accompanying signs and symptoms. The report is based on two cases. Cerebral blood flow imaging was performed by SPECT using 99m Tc-HMPAO complex. The images obtained showed crossed cerebellar diaschisis in both cases. Remote and opposite blood flow disturbances could be the reason for dysfunction, possible symptoms and clinical signs no matter whether CT imaging does or does not display lesions. Diaschisis may be a defense mechanism of the damage brain.