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.