Dysplastic gangliocytoma of the cerebellum is a rare disorder requiring surgical resection. During surgical exploration, the margin with normal cerebellar tissue is often not distinct. We present here a case in which we surgically treated a patient with Lhermitte-Duclos disease, and discuss radical resection of the tumour. The patient was first admitted at the age of 34 years. A MRI scan revealed a large left cerebellar mass typical of dysplastic gangliocytoma. Postoperatively the patient developed severe cerebellar syndrome with only partial recovery after 4 years. MRI revealed no impairment of cerebrospinal fluid circulation; the mass in the left cerebellum had been removed, and no recurrent disease was visible. Clinical problems after gross total or complete removal of Lhermitte-Duclos lesions have not been reported in the literature, but herein we stress the importance of extreme caution in removing these lesions in cerebellar areas that have no distinct border between the tumour and normal tissue.