The prognosis for patients with malignant gliomas remains poor, and novel treatment paradigms are needed. Radioimmunotherapeutic drugs have been studied in clinical trials as adjuncts to treatment for these tumors. One such agent is (131)I-chTNT-1/B mAb (Cotara(®)), a compound locally delivered to the tumor site through convection-enhanced delivery. It is a genetically engineered chimeric monoclonal antibody that binds to the DNA-histone H1 complex, and carries (131)I, which locally delivers its radioactive payload to kill adjacent tumor cells. Clinical experience with Cotara is emerging; completed Phase I and II trials with a total of 51 patients helped to define dosing regimens for the drug. A recent Phase II dose-confirmation trial with Cotara for patients with glioblastoma multiforme at first relapse has demonstrated promising overall survival results of 41 weeks. This review explores the clinical experience of radioimmunotherapy and describes the role of Cotara for treatment of patients with malignant gliomas.