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For many years, the cerebellum is traditionally regarded as an organ that subserves coordination, balance, gait, and fine motor control. Today, novel findings gathered from neuroanatomical research and modern functional neuroimaging studies point out the importance of the cerebellum involvement in the pathophysiology of psychiatric disorders. There is converging evidence suggests that schizophrenia may be associated with cerebellar anomalies and a cerebellar dysfunction could underlie some of the clinical psychiatric and neurological symptoms as well as cognitive dysfunctions observed in schizophrenia. Moreover, involvement of cerebellar dysfunction has been suggested in the pathogenesis of Obsessive–Compulsive Disorder (OCD) and schizophrenia- OCD comorbidity. Dandy-Walker complex (DWC) is a series of anomalies in the posterior fossa, including Dandy–Walker malformation, Dandy–Walker variant, mega-cisterna magna and posterior fossa arachnoid cyst. Mega cisterna magna is the mildest form of “Dandy-Walker complex” and a developmental variation of the posterior fossa characterized by the enlargement of the cisterna magna, morphologically intact vermis and cerebellar hemispheres. According to our knowledge in literature, there is a case report about Dandy Walker continuum with schizophrenia comorbid with OCD. Our aim is to present here a case of schizophrenia comorbid with OCD and mega cisterna magna. A 57-year-old female applied to our psychotic disorders outpatient clinic with a complaint of intrusive urges to say some words, which she didn’t want to say and a fear of being heard from other people. In her history, there were several hospitalizations with paranoid, persecutory delusions and visual hallucinations. There was no history of psychiatric disorders in the patient’s family. In her mental examination, her affect was blunted, in her thought content there were doubt and aggression obsessions accompanied by mental compulsions. At the time of application, she had been taking 4 mg risperidone and 300 mg quetiapine per day. In her neurological examination, there was no significant finding and electroencephalography was unremarkable. Cranial Magnetic Resonance Imaging (MRI) scan disclosed ‘‘mega cisterna magna’’. In this case, mega cisterna magna and schizo-obsessive symptoms may be found together coincidentally or any cerebellar dysfunction due to mega cisterna magna may contribute to the occurrence of some psychotic symptoms and obsessions. Such neurostructural variants may offer an insight into a better understanding of the neurodevelopmental models underlying schizophrenia comorbid with OCD.