The treatment of recurrent malignant glioma is difficult and at present largely disappointing. Furthermore the results of any treatment modality need to be interpreted with knowledge regarding patient selection and timing of treatment. The results of interstitial brachytherapy using iodine-125 in 23 patients are presented. There were no operative complications. Median survival time from tumour recurrence and implantation was 36 and 25 weeks respectively. Karnofsky Performance Status (KPS) was significantly associated with survival, though patient age, original tumour histology, prior chemotherapy, and time to recurrence were not. Treatment does confer modest survival benefit as compared to controls, but our results are not as impressive as others. Reasons for this finding are discussed.