Among new therapeutic modalities for both primary and secondary brain tumors, selective manipulation of metabolic pathways seems attractive. In human malignant gliomas and cell lines from a glioblastoma multiform, lonidamine has been shown to interfere with aerobic glycolysis with a decrease of lactate production by the inhibition of a mitochondrially-bound hexokinase; this selective reduction of the energetic capabilities of glioma cells would be a limiting factor for processes requiring energy, such as cell growth and recovery from potentially lethal damage after radiotherapy or chemotherapy. The activity of lonidamine in malignant gliomas after surgery in association with conventional radiotherapy is being investigated, while previous studies have suggested a limited, but clear therapeutic activity of the drug in recurrent malignant gliomas. In brain metastases lonidamine has not been effective as a radiation enhancer, but has been shown to potentiate systemic chemotherapy. Most common side effects were myalgias, testicular pain and ototoxicity with no serious organ toxicity or myelosuppression.