Two patients with malignant gliomas located in the frontal lobe were treated by supraophthalmic intracarotid infusion of high-dose ACNU 15 mg/kg (ca. 600 mg/m2) combined with a total 60 Gy of irradiation after surgery. Irradiation therapy was started 13 days (case 1) and 10 days (case 2) after surgery, and single chemotherapy with ACNU 1,020 mg (case 1) and 1,100 mg (case 2) was performed when 36 Gy of whole brain irradiation was done. Chemotherapy was followed by autologous bone marrow transplantation containing 6.8 X 10(9) and 8.9 X 10(8) nucleated cells, respectively. Nadirs of white cell counts on 9 days in case 1 and 14 days in case 2 after chemotherapy were 280 cells and 240 cells/mm3, respectively, and the white cell counts less than 1,000/mm3 continued for 7 and 12 days, respectively. Local irradiation was started again when the number of white cells became more than 1,000/mm3 and 24 Gy was completed in each case. CT scanning carried out on discharge demonstrated no apparent abnormal high density area by contrast medium in both cases. These two patients did not show severe side effects at 10 months in case 1 and at 3 months in case 2 after high dose ACNU therapy, and remained progression-free at that time. Dose 15 mg/kg of ACNU may be the maximum tolerable dose patients can recover from severe myelosuppression, caused by high dose ACNU therapy combined with irradiation therapy, by marrow rescue.