The uridine diphosphate glucuronosyltransferase (UGT) gene 1A1*6 polymorphism, which affects irinotecan metabolism, has been associated with improved survival in lymphoma patients treated with of carboplatin, dexamethasone, etoposide and irinotecan (CDE-11). This study assessed the efficacy of CDE-11 relative to the UGT1A1*6 polymorphism in 27 elderly patients with relapsed or refractory diffuse large B-cell lymphoma who were ineligible for high-dose chemotherapy plus autologous stem cell transplantation. The 2-year survival rate after initial CDE-11 treatment was significantly higher in patients with than without UGT1A1*6 (57% vs. 5%). The most common grade 4 adverse event in patients with the UGT1A1*6 genotypes was neutropenia (88.9%), but there were no gastrointestinal adverse events or treatment-related deaths. Disease progression was the most frequent cause of death. CDE-11 was well tolerated and provided clinical benefit to elderly patients with relapsed or refractory diffuse large B-cell lymphoma. The response to CDE-11 likely correlated with UGT1A1*6 polymorphisms, but further prospective studies are warranted to optimize irinotecan-based chemotherapies relative to UGT1A1 polymorphism.