Data from a phase III trial involving patients with 1p/19q non-co-deleted anaplastic glioma indicate that adjuvant temozolomide, administered either concurrent with, or immediately following radiotherapy, provides a significant improvement in overall survival duration, compared with radiotherapy alone (HR 0.65; P = 0·0014). Grade 3–4 adverse events, which were mostly haematological, were observed in 8–12% of patients. Whether or not temolozomide administered concurrently with radiotherapy is superior to temozolamide following radiotherapy has yet to be revealed.