Abstract Background. Despite the advent of new treatment strategies, many patients with diffuse large B-cell lymphoma (DLBCL) relapse or die of the disease. Prospective clinical trials have demonstrated that lenalidomide is an effective and safe treatment option, especially for non-germinal center B-cell (non-GCB) DLBCL. However, routine clinical data are lacking, which is why we provide the results of the so-far largest relapsed/refractory (R/R) DLBCL real-life analysis. Methods. We retrospectively assessed 123 R/R DLBCL patients who received either 15 or 25 mg/day of lenalidomide from January 2006 to January 2015. Results. During a median follow-up period of 4.5 years, complete remission was achieved in 32% and a partial remission in 33% non-GCB patients compared with 0% and 3% in the GCB group (p < .001 and .001, respectively), with median response durations of 15 and 5 months, respectively (p < .001). Lenalidomide at 25 mg was superior to 15 mg in terms of response (complete remission 21% and partial remission 23% vs. 0% and 8%; p = .007 and .05) and median response duration (10 vs. 4 months; p = .03). Toxicity was limited and reversible. Median progression-free survival differed between non-GCB and GCB patients (37 vs. 30 months; p < .001) and between the two dosages (24 vs. 34 months; p = .002). However, overall survival was similar between the subgroups (38–42 months). Conclusion. We provide evidence that lenalidomide is a valid treatment option for R/R DLBCL, with limited and reversible toxicity, and is more efficient in non-GCB DLBCL and at higher doses.