Background <p>The significant financial costs associated with solid-organ and bone marrow transplantation incurred by the United States’ (U.S.) health systems are well documented. However, the out-of-pocket (OOP) costs and the risk of financial toxicity — defined as economic stress from OOP expenses relative to available resources — for transplant recipients remain poorly characterized.</p> Methods <p>We assessed annual OOP medical expenses for transplant recipients using the Medical Expenditure Panel Survey (MEPS) from 2016 to 2020 (<i>n</i> = 201 patients representing <i>N</i> = 466,016) and calculated yearly medical care expenses and insurance premiums. Logistic regressions were performed to analyze risk factors for financial toxicity, using income category and insurance status as indicators of socioeconomic status.</p> Results <p>The mean annual OOP expense was $4034 (SE 508), with insurance premiums and medications being the most significant costs. Among transplant recipients, 12% (SE 3) experienced high financial toxicity. Low-income patients, compared to high-income patients, were nine times more likely to experience financial toxicity (OR 9.3, <i>p</i> = 0.001), with privately insured low-income patients at the highest risk (OR 7.4, <i>p</i> &lt;0.001). Financial toxicity was associated with delayed medication refills due to costs (12% vs 3%, <i>p</i> &lt; 0.05), poorer perceived health status (27% vs 9%, <i>p</i> = 0.05), and increased anxiety (47% vs 20%, <i>p</i> &lt; 0.05).</p> Conclusions <p>Low-income transplant recipients with private insurance are particularly vulnerable to financial toxicity. Future research should examine the health effects of financial toxicity to enable development of health system and policy interventions aimed at mitigating financial toxicity in this population.</p>