PURPOSE Concomitant temozolomide (TMZ)/radiotherapy followed by adjuvant TMZ has increased survival in patients with glioblastoma multiforme (GBM). However, few options are effective for patients who experience treatment failure. We conducted a multicenter, phase II study to assess the efficacy and safety of continuous dose-intense TMZ for recurrent GBM. PATIENTS AND METHODS Patients with malignant glioma at progression after standard TMZ 150 to 200 mg/m(2) x 5 days in a 28-day cycle for three or more cycles were stratified by tumor type (anaplastic glioma group A, GBM, group B). Ninety-one patients with GBM were prospectively divided into three groups (early [B1], extended [B2], and rechallenge [B3]) according to the timing of progression during adjuvant therapy. All patients received continuous dose-intense TMZ 50 mg/m(2)/d for up to 1 year or until progression occurred. Response was assessed by using RECIST (Response Evaluation Criteria in Solid Tumors). Results A total of 116 of 120 patients were evaluable for efficacy. For patients with GBM, 6-month progression-free survival (PFS) was 23.9% (B1, 27.3%; B2, 7.4%; B3, 35.7%). One-year survival from time of study entry was 27.3%, 14.8%, and 28.6% for the B1, B2 and B3 groups, respectively. For patients with anaplastic glioma, 6-month PFS was 35.7%; 1-year survival was 60.7%. The most common grades 3 and 4 nonhematologic toxicities were nausea/vomiting (6.7%) and fatigue (5.8%). Grades 3 and 4 hematologic toxicities were uncommon. CONCLUSION Rechallenge with continuous dose-intense TMZ 50 mg/m(2)/d is a valuable therapeutic option for patients with recurrent GBM. Patients who experience progression during the first six cycles of conventional adjuvant TMZ therapy or after a treatment-free interval get the most benefit from therapy.