Chimeric antigen receptor (CAR) T-cell therapy is associated with potentially severe toxicities that create a substantial burden for patients. Patient-reported outcomes (PROs) offer valuable insights into symptoms, functioning, and other complex constructs of interest. In this Review, we aimed to identify symptom and impact concepts important to patients receiving CAR T-cell therapy, construct a conceptual framework for an electronic patient-reported outcome (ePRO) system, and identify timepoints to capture PRO data for CAR T-cell therapies.