BACKGROUND: The number of Medicaid beneficiaries has increased under the Affordable Care Act, improving access to solid organ transplantation in this disadvantaged patient cohort. It is unclear what impact Medicaid expansion will have on transplantation outcomes. We performed a retrospective cohort analysis to measure the frequency and variation in Medicaid transplantation and post-transplantation survival in Medicaid patients. STUDY DESIGN: Adult heart, lung, liver, and renal transplant recipients between 2002 and 2011 (n = 169,194) reported to the Scientific Registry of Transplant Recipients were identified. Transplant recipients were classified based on insurance status (private, Medicare or Medicaid). Outcomes measures included 5-year post-transplantation survival, summarized using Kaplan-Meier curves and compared with log-rank tests. Organ-specific Cox proportional hazards models were used to adjust for donor and recipient factors. RESULTS: Medicaid patients comprised 8.6% of all organ transplant recipients. Fewer transplantations were performed than expected among Medicaid beneficiaries for all organs except liver (liver: observed to expected ratio = 1.21; 95% CI, 0.68-1.90; heart: observed to expected ratio = 0.89; 95% CI, 0.44-1.49; lung: observed to expected ratio = 0.57; 95% CI, 0.22-1.06; renal: observed to expected ratio = 0.32; 95% CI, 0.08-0.72). Medicaid transplant recipients were listed with more severe organ failure and experienced shorter transplant wait times. Post-transplantation survival was lower in Medicaid patients compared with private insurance for all organs. Post-transplantation survival in Medicaid patients was similar to Medicare patients for heart, liver, and renal but lower in lung. CONCLUSIONS: Medicaid organ transplant beneficiaries had significantly lower survival compared with privately insured beneficiaries. The more severe organ failure among Medicaid beneficiaries at the time of listing, suggested a pattern of late referral, which might account for worse outcomes. Implementation of the Affordable Care Act gives the opportunity to develop the necessary infrastructure to ensure timely transplantation referrals and improve long-term outcomes in this vulnerable population.