1528 Background: Up to 30% of PCNSL patients (pts.) are refractory to primary therapy and about 60% relapse. Salvage therapy prolongs survival in PCNSL, however, no standard regimen has been defined. Topotecan reaches therapeutic levels in CNS and showed activity in aggressive lymphomas. Methods: Immunocompetent pts. with relapsed or refractory PCNSL were treated with topotecan 1.5 mg/m2 d1–5 iv. every 3 to 4 weeks (depending on hematological recovery). Response was evaluated by MRI or CT scan after