Primary malignant lymphoma is a non-Hodgkin lymphoma which occurs in the brain in the absence of systemic involvement. A 63-year-old woman presented to emergency service, complaining of sudden onset vomiting and dizziness. She was unconscious when she was admitted to the hospital. She had no complain, until a week ago when she experienced a headache nonresponding to analgesic. Preliminary diagnosis was cerebrovascular hemorrhage or intracranial mass. Magnetic resonance imaging and PET/CT yielded a mass filling all ventricles. Histopathology of the mass matched with malignant lymphoma located in the ventricles.