Introduction: Immune-checkpoint inhibitors have been approved for first and second line treatments of metastatic non-small cell lung cancer based on the results of several phase III trials. Patients with organ transplantation were excluded from these studies because checkpoint inhibitors could activate allo-reactive T cells leading to acute graft rejection. Case report: A 71-year-old Caucasian-male was diagnosed with stage IV pulmonary adenocarcinoma with multiple metastases, without molecular alteration and negative PD-L1 status. He had a left kidney transplant, and his immunosuppressive regimen consisted of sirolimus and mycophenolate mofetil. After failure of two therapeutic lines (carboplatin-paclitaxel and erlotinib) a multidisciplinary oncology meeting with the nephrologist started third line treatment with nivolumab 3mg/kg every 15 days, with no modification of the immunosuppressive treatment. The patient received a total of 14 injections of nivolumab with stable disease but treatment was discontinued due to acute rejection of the transplanted kidney 6 months later, without need for dialysis. The patient died of a chylothorax related to progression of the tumour 12 months after initiation of nivolumab. Conclusion: Immune checkpoint inhibitors are a potential treatment for solid organ transplant patients despite the risk of graft rejection.