In this study, the health impacts of improving access to treatment with axicabtagene ciloleucel (axi-cel) was assessed in patients with relapsed/refractory diffuse large B-cell lymphoma after ≥2 lines of therapy in Spain. A partitioned survival mixture cure model was used to estimate the lifetime accumulated life years gained (LYG) and quality-adjusted life years (QALYs) per patient treated with axi-cel versus chemotherapy. Efficacy data were extracted from the ZUMA-1 trial for axi-cel and from the SCHOLAR-1 study for chemotherapy. In the base case, the incremental outcomes of axi-cel versus chemotherapy were evaluated in a cohort of 187 patients treated with CAR T-cell therapies, as reported by the "Spanish National Health System Plan for Advanced Therapies", and in the alternative scenario in the full eligible population based on epidemiological estimates (n = 490). Taking those currently treated with axi-cel, compared with chemotherapy, axi-cel provided an additional 1341 LYGs and 1053 QALYs. However, when all eligible patients (n = 490) were treated, axi-cel provided an additional 3515 LYs and 2759 QALYs. Therefore, if all eligible patients were treated with axi-cel rather than those currently treated as per the registry (n = 187), there would have been an additional 303 patients treated, resulting in an additional 2173 LYGs and 1706 QALYs in total. The lack of access in Spain has led to a loss of a substantial number of LYGs and QALYs, and efforts should be made to improve access for all eligible patients.