Here we report on a Jehovah's Witness (JW) patient who experienced profound and prolonged life-threatening cytopenias following CD19-targeted CAR T cell therapy, successfully managed with bloodless medicine strategies. This case highlights the potential risks of CAR T therapy, even in patients without known hematotoxicity risk factors. By implementing tailored bloodless strategies, the patient received CAR T therapy without significant infectious, cardiac, or bleeding complications. Remarkably, they remain in remission 5 years later with normal blood counts. This underscores the viability of CAR T cell therapy for JW patients, emphasizing the importance of careful patient selection and risk-benefit deliberation. Further research into severe cytopenias post-CAR T therapy is critically needed. : The authors have confirmed clinical trial registration is not needed for this submission.