We report a case of a 56-year-old woman admitted to our hospital for status epilepticus. Three months before hospitalization, the patient underwent gross total removal of a glioblastoma with BCNU wafer implantation in the left parietal lobe. The cavity was subsequently lined with five BCNU wafers. After admission, magnetic resonance imaging(MRI)showed cyst formation accompanied by strong edema, with no recurrence of glioblastoma. She was initially administered antiepileptic drugs and glycerol with betamethasone, after which her seizures stopped but recurred one month later due to a decrease in betamethasone. The BCNU wafers were removed four months after the initial surgery, after which the seizures completely stopped. Histopathological examination of the cavity indicated the presence of inflamed tissue and no recurrence of glioblastoma. Neurosurgeons should be aware of the possibility of cyst formation after BCNU wafer implantation for malignant gliomas. In this manuscript, we provide a case presentation and a review of the literature.