Purpose: Anaplastic oligodendroglioma is a chemosensitive glial neoplasm. To improve disease control and postpone cranial radiotherapy, we designed a phase II study of intensive procarbazine, lomunstine and vincristine followed by high-dose thiotepa with autologous stem cell rescue for patients with newly diagnosed anaplastic or aggressive oligodendroglioma. Patients and methods: Sixty-nine patients with a median age of 42 (range: 18-67) and a median Karnofsky Performance Score of 90 (range: 70-100) were enrolled. Sixteen patients had a prior diagnosis of low-grade oligodendroglioma and 16 had mixed oligoastrocytoma pathology. Only patients with demonstrably chemosensitive enhancing tumors or those free of enhancing tumor after surgery and induction therapy were eligible to receive high-dose thiotepa. Results: Thirty-nine patients (57%) completed the transplant regimen; their estimated median progression-free survival is 69 months and median overall survival has not been reached. Twelve transplanted patients (31 %) relapsed. Neither histology nor prior low-grade oligodendroglioma correlated with relapse; however, persistent non-enhancing tumor at transplant conferred an increased risk of relapse (p = 0.028). The transplant regimen was well-tolerated; median hospital stay was 20 days (range: 7-43) with a median time to ANC and platelet engraftment of 10 days. Thirty patients (43%) did not receive high-dose thiotepa because of stable or progressive disease (n = 21), excessive toxicity (n = 4), refusal of further therapy (n = 2), failure to obtain insurance coverage (n = 2), or other (n - 1). No treatment-related or long-term neurotoxicity was seen in the transplanted patients. Conclusions: High-dose chemotherapy with stem cell rescue as initial treatment for anaplastic oligodendroglioma is feasible and associated with prolonged tumor control in some patients.