Dyke–Davidoff–Mason syndrome is an extremely rare medical condition that results from brain damage occurring during foetal life or early childhood. The aetiology of the syndrome can be congenital or acquired. The clinical presentation of the syndrome is variable, and depends on the extent of damage to the central nervous system. It most commonly manifests as epileptic seizures, intellectual disability, and hemiparesis/hemiplegia, which is usually preceded by the first seizure. It is suspected that intellectual impairment is a consequence of epilepsy. The spectrum of symptoms also includes psychiatric conditions, particularly psychotic disorders and mood disorders. Radiological manifestations of the syndrome include midline cerebral shift, widening of the Sylvian fissure, hemispheric aplasia/hypoplasia of the brain, ipsilateral cranial bone thickening, lateral ventricle enlargement, as well as hyperpneumatisation of the frontal and sphenoid bones, and the mastoid process. Diagnosis is mainly based on imaging tests such as computed tomography and magnetic resonance imaging, as well as neurological examination and electroencephalography. During the patient’s history-taking, particular attention should be paid to pregnancy history and the childhood period in order to identify potential etiological factors. No characteristic changes in laboratory tests indicating Dyke–Davidoff–Mason syndrome have been found. Treatment is primarily symptomatic. The greatest challenge for physicians is the control of epileptic seizures. Conservative treatment is initially employed. If proven to be ineffective, surgical treatment should be considered.