Ongoing brain tumor clinical trials by the Japan Clinical Oncology Group (JCOG) are:JCOG1016, phase III randomized study in patients with anaplastic glioma of radiotherapy with temozolomide versus nimustine hydrochloride (ACNU) followed by temozolomide, is to prove superiority of post-operative radiotherapy with ACNU. JCOG1114, phase III study of high-dose methotrexate and whole brain radiotherapy with or without concomitant and adjuvant temozolomide in patients with primacy CNS lymphoma, is to prove usefulness and get insurance approval of TMZ for primary CNS lymphoma. JCOG1303, randomized phase III study for unresectable WHO Grade II diffuse astrocytoma with radiotherapy alone or chemoradiotherapy with temozolomide, is to prove superiority of STUPP regimen over simple radiotherapy for newly diagnosed and unresectable diffuse astrocytoma. JCOG1308, a multicenter randomized phase III study for recurrent glioblastoma comparing bevacizumab alone with dose-dense temozolomide followed by bevacizumab, is to prove usefulness of dose-dense, 7 days on/7 days off, TMZ, and to approve insurance coverage for recurrent GBM. JCOG1703, a multicenter randomized phase III study for newly-diagnosed maximally resected glioblastoma comparing carmustine wafer implantation followed by Stupp regimen with Stupp regimen alone, is to prove the survival advantage of surgery of GBM using carmustine wafer.