||BACKGROUND: By assessing the spectrum of hematologic malignancies associated with solid-organ transplantation in the elderly, we provide information on the pathogenesis of lymphoid and myeloid neoplasms and the clinical manifestations of immunosuppression. METHODS: Using data from the U.S. Surveillance, Epidemiology, and End Results Medicare database, we identified 83,016 cases with a hematologic malignancy (age 66-99 years) and 166,057 population-based controls matched to cases by age, sex, and calendar year. Medicare claims were used to identify a history of solid-organ transplantation. We used polytomous logistic regression to calculate odds ratios (OR) comparing transplantation history among cases with various hematologic malignancy subtypes and controls, adjusting for the matching factors and race. RESULTS: A prior solid-organ transplant was identified in 216 (0.26%) cases and 204 (0.12%) controls. Transplantation was associated with increased risk for non-Hodgkin lymphomas [OR, 2.13; 95% confidence interval (95% CI), 1.67-2.72], especially diffuse large B-cell lymphoma (OR, 3.29; 95% CI, 2.28-4.76), marginal zone lymphoma (OR, 2.48; 95% CI, 1.17-5.22), lymphoplasmacytic lymphoma (OR, 3.32; 95% CI, 1.41-7.81), and T-cell lymphoma (OR, 3.07; 95% CI, 1.56-6.06). Transplantation was also associated with elevated risk of Hodgkin lymphoma (OR, 2.53; 95% CI, 1.01-6.35) and plasma cell neoplasms (OR, 1.91; 95% CI, 1.24-2.93). Risks for myeloid neoplasms were also elevated (OR, 1.99; 95% CI, 1.41-2.81). CONCLUSION: Solid-organ transplantation is associated with a wide spectrum of hematologic malignancies in the elderly. Risk was increased for four specific non-Hodgkin lymphoma subtypes for which a viral agent has been implicated, supporting an added role for immunosuppression. IMPACT: Our results support monitoring for a wide spectrum of hematologic malignancies following solid-organ transplant.