Aim: High-grade glioblastoma multiforme (GBM) has a poor median overall survival (OS). The standard treatment after surgery is temozolomide and radiotherapy (RTH). Patients with unmethylated methylguanine-methyltransferase promoter (MGMT) have no or little benefit from temozolomide and are eligible for alternative therapies. Gemcitabine is a good radiosensitizer. We aimed to evaluate the combination of gemcitabine with RTH in newly diagnosed GBM. Methods: The study was a prospective phase II study. Eligible patients were required to have histologically proven anaplastic astrocytoma or GBM. Patients underwent biopsies or subtotal resection. The treatment consisted of fixed-dose rate gemcitabine 175 mg/m2 weekly followed after 24 h by standard cranial RTH for 6 weeks. Tumor response was evaluated by Macdonald criteria. In case of progression, patients received temozolomide (200 mg/m2/5 days every 28 days). Results: Thirty patients with a median age of 52 years (30-69), 73%/27% male/female, the Eastern Cooperative Oncology Group performance status 1 (range 0-2) were enrolled. Five patients had a partial-response (17%) and 13 stable-disease (43%). Median time to progression was 7.88 months (95% CI 6.1-9.69) and OS was 11.77 months (95% CI 9.97-13.56). The treatment was well tolerated with grade-3 neutropenia in 3, grade-3 anemia in 2 and impaired liver enzymes in 1 patient. Conclusion: Gemcitabine followed by radiotherapy is active and promising regimen in newly diagnosed GBM. Gemcitabine uptake is easy, with a long local retention of active metabolites, precluding systemic side effects of radiosensitization. In a phase III study this treatment should be evaluated in patients with unmethylated MGMT promoter who will not benefit from temozolomide.