CD19-chimeric antigen receptor T-cell (CAR T-cell) therapy has improved the outcomes of relapsed/refractory large B cell lymphoma significantly. However, about 50% of patients relapsed post-CAR-T therapy. Late relapse composed of 1/3 to 1/2 of CAR-T cell therapy failure, with no previous reports of isolated relapse in immune-privileged sites. Here, we report the first case series of late-onset post CAR-T cell therapy isolated central nervous system (CNS) relapses, in systemic relapsed/refractory large B cell lymphoma patients. With these cases, we suggest that additional CNS prophylaxis should be administrated for primary refractory patients on CAR-T cell therapy with previous neurological involvements, multiple extra-nodular lesions, and high CNS-IPI score pre-CAR, as well as early disappearance of circulating CAR-T cells post infusion.