Cerebral hemiatrophy (or Dyke-Davidoff-Masson Syndrome) is a neurodevelopmental disorder characterized by atrophy or hypoplasia of one cerebral hemisphere accompanied by ipsilateral calvarial changes. Clinically, the condition presents with contralateral motor dysfunction, facial asymmetry, epilepsy and intellectual impairment. Psychiatric manifestations are uncommon and the neuropsychiatric aspect of the disease is not wet described. Here, we report a 26-year-old female who presented with left cerebral hemiatrophy and schizoaffective disorder. We discuss the relevance of left-sided neurodevelopmental cerebral atrophy in the context of disrupted neural development of brain lateralization, plasticity, and evidence regarding left hemisphere dysfunction in schizophrenia and schizoaffective disorder.