Glioblastoma is the most common and aggressive primitive brain tumor in adults. Temozolomide (TMZ) administered daily with radiation therapy, followed by adjuvant TMZ has become the standard treatment. Although TMZ treatment has been considered to have a low toxicity profile, studies have noted the development of a severe myelosuppression, especially during the concomitant treatment; this toxicity may in some cases be prolonged and consequently treatment must be definitively discontinued. We analyzed two cases treated at our oncological center who developed severe and prolonged hematological toxicity during concomitant chemoradiotherapy treatment with TMZ. Hypothesizing that radiation therapy and daily TMZ could be the major causes of severe hematological toxicity during the concomitant phase, we decided to treat both patients with maintenance TMZ at the time of recovery of hematological values. Patients showed good tolerability without important myelosuppression. In conclusion, we suggest that glioblastoma patients with severe myelotoxicity during daily TMZ and radiation therapy be treated with maintenance TMZ at the time of blood value recovery.