Outcome data of patients with relapsed/refractory (R/R) diffuse large B-cell lymphoma (DLBCL) beyond the second line are scarce outside of clinical trials. Novel therapies in the R/R setting have been approved based on single-arm trials, but results need to be contextualized by real-world outcomes. Medical records from 3753 Danish adults diagnosed with DLBCL were reviewed. Patients previously treated with rituximab and anthracycline-based chemotherapy who received the third or later line (3 L+) of treatment after 1 January 2015, were included. Only 189 patients with a median age of 71 years were eligible. The median time since the last line of therapy was 6 months. Patients were treated with either best supportive care (22%), platinum-based salvage therapy (13%), low-intensity chemotherapy (22%), in clinical trial (14%) or various combination treatments (32%). The 2-year OS-/PFS estimates were 25% and 12% for all patients and 49% and 17% for those treated with platinum-based salvage therapy. Age ≥70, CNS involvement, elevated LDH and ECOG ≥2 predicted poor outcomes, and patients with 0–1 of these risk factors had a 2-year OS estimate of 65%. Only a very small fraction of DLBCL patients received third-line treatment and were eligible for inclusion. Outcomes were generally poor, but better in intensively treated, fit young patients with limited disease.