Background: The outcome of patients with CNS relapse of aggressive lymphoma (secondary CNS lymphoma, SCNSL) is poor with no standard therapy established thus far. Here we present the final analysis of a prospective multicenter phase II study using an intensive induction regimen followed by high-dose chemotherapy and autologous stem-cell transplantation. Methods: Adult immunocompetent patients ≤65 years with SCNSL were eligible. Induction chemotherapy consisted of two cycles MTX/IFO (methotrexate 4g/m² iv. d1, ifosfamide 2g/m² iv. d3-5 and i.th. liposomal cytarabine 50mg d6) and one cycle AraC/TT (cytarabine 3g/m² d1-2, thiotepa 40mg/m2 iv. d² and i.th. liposomal cytarabine 50mg d3). Then, patients without progression received high-dose chemotherapy with carmustine 400mg/m2 iv. d -5, thiotepa 2x5mg/kg iv. d -4 to -3 and etoposide 150mg/m² iv. d -5 to -3 followed by ASCT d0. Results: Thirty eligible patients (median age 58 years) were enrolled. Three patients had T-cell and 27 aggressive B-cell lymphoma. Pre-treatment was CHOP-like in 29 patients, including rituximab in 26. CNS relapse occurred after a median of 8.5 (3-80) months and was intracerebral in 23 and meningeal in13 patients (combined in 7); 6 had concomitant systemic lymphoma. After induction therapy CNS response was found in 22 (73%) patients (8xCR, 14xPR), 3 patients had SD, 4 patients PD and 1 patient no response evaluation. HD-ASCT was performed in 24 patients; resulting in 15 CR (63%), 2 PR (8%) and 7 PD (29%). Myelotoxicity was the most frequent WHO grade 3-4 adverse event with infections in 8/30 pts on MTX/IFO (27%), 5/23 (22%) on AraC/TT and 11/20(55%) on HD-ASCT. One patient died due to septic diverticulitis and one developed persisting fecal incontinence. The median follow up was 21 months. The median PFS was 12.1 months (95% CI 6.4-17.7) in all patients and 30.4 (95%CI 2.5-58.3) months after HD-ASCT, the median overall survival was 27.4 months and not reached, respectively. Conclusions: This first prospective study on SCNSL demonstrates that lasting remissions can be achieved with CNS-directed HD-ASCT in a large proportion of patients and probably cure in some.