The study objective is to describe a clinical case of a rare disorder of the cerebellum, Lhermitte–Duclos disease.Clinical case. The Federal Neurosurgical Center (Novosibirsk) admitted a male patient, 40 years old. Medical history showed that in 2017 he underwent ventriculoperitoneal shunt due to hypertensive hydrocephalus syndrome caused by space-occupying mass of the right hemisphere of the cerebellum. In June of 2017, the patient was consulted by a neurosurgeon. Later, an increase in the mass, partial atrophy of the optic disks were observed. Due to the patient’s complaints of headache, ataxia, vertigo, as well as insufficient effect of the shunt, microsurgical removal of the space-occupying mass in the cerebellum by right paramedian suboccipital craniotomy was performed. Gangliocytoma removal was performed under constant neurophysiological control which allowed to fully resect the gangliocytoma inside intact brain tissue. Histological and immunohistological examinations allowed to diagnose grade I dysplastic gangliocytoma of the cerebellum (Lhermitte–Duclos disease). In the postoperative period, brain symptoms regressed fully, vestibulocerebellar syndrome persisted. The patient was discharged in satisfactory condition. No negative dynamics were observed in 7 months of follow-up.Conclusion. Due to the rareness of Lhermitte–Duclos disease, currently there are no established approaches to treatment, however, in symptomatic course there are indications for surgical removal of the gangliocytoma. Radicality of resection should be correlated with the risk of neurological defects. In our case, surgical treatment allowed to improve the patient’s condition, prevent further progression of the gangliocytoma and obtain an accurate histological diagnosis.