BACKGROUND: Belatacept is a costimulatory blocker that can be used to prevent and treat rejection in lung transplant recipients (LuTRs). The epidemiology of infections in belatacept-treated LuTRs has not been systematically evaluated. METHODS: We performed a single-center retrospective study of all adult LuTRs who received belatacept as prevention or treatment of antibody-mediated rejection (desensitization) or as part of maintenance immunosuppression from January 1, 2011, to June 30, 2022. We assessed the epidemiology of infections that occurred within 12 months following the first belatacept dose. RESULTS: Fifty-two LuTRs received at least one dose of belatacept as either desensitization (n = 32) or maintenance immunosuppression (n = 20). Among 45 patients who were cytomegalovirus (CMV) donor and/or recipient seropositive, nine (20%) developed CMV infection. Seven (77%) CMV infections occurred despite valganciclovir prophylaxis and four (44%) were associated with antiviral resistance. Three (6%) LuTRs developed Epstein-Barr virus (EBV) associated post-transplant lymphoproliferative disorder (PTLD). Twenty-five (48%) LuTRs developed 43 bacterial infections and five (10%) developed proven or probable invasive fungal disease. Incidence rates of viral, bacterial, and fungal infections were similar between the desensitization and maintenance groups: incidence rate ratios (95% confidence interval) were 0.70 (0.32-1.57), 1.31 (0.70-2.46), and 2.82 (0.31-25.2), respectively. Infection/PTLD prompted belatacept discontinuation in eight (15%) patients. CONCLUSIONS: In the first year after belatacept initiation, LuTRs commonly developed CMV infections, EBV+ PTLD, and bacterial infections. Multicenter collaborations are needed to better understand infection risks in LuTRs treated with belatacept.