46 eligible patients with either anaplastic astrocytoma (AA) or glioblastoma (GBM) and clinical and computed-tomography-confirmed relapse following primary surgery and radiotherapy received oral tauromustine 130 mg/m2 every 5 weeks. A prospective design allowed for concurrent assessment of both clinical and radiological responses and drug toxicity. 41% of patients improved clinically whilst 46% improved radiologically with 3 complete, 7 partial and 7 minimal responses (WHO criteria). Toxicity included grade III or IV gastrointestinal side-effects (15%), grade III or IV leukopenia (24%) and grade III and IV thrombocytopenia (44%). In 9 clinically responding patients, haematological toxicity led to discontinuation of treatment. All patients were followed-up until death and second-line chemotherapy was not used. Median post-treatment survival was 26 weeks for patients with GBM and 57 weeks for patients with AA. Overall 2-year survival rate was 69% for AA and 23% for GBM. Tauromustine given at the time of relapse has demonstrable antitumour activity in patients not previously treated with chemotherapy.