We describe a case of hemitrophy in a 12-year-old child presenting with 
seizures, hemiplegia and mental retardation. Hemiatrophy of one cerebral 
hemisphere is not frequently encountered in clinical practice. When this 
develops early in life (during the first two years), certain cranial changes 
like ipsilateral hypertrophy of the skull and sinuses occur. Asymmetry of 
cerebral hemispheric growth with atrophy on one side, ipsilateral osseous 
hypertrophy and hyper-pneumatization of sinuses with contralateral paresis are 
features of Dyke Davidoff Masson Syndrome (DDMS). Probably vascular occlusion 
was most important cause of hemiatrophy in our case.