Abstract. Background: In December 2000, Medicare eliminated time limitations in immunosuppressant coverage after kidney transplant for beneficiaries age 65 and those who were disabled. This change did not apply to younger non-disabled beneficiaries who qualified for Medicare only because of their end-stage renal disease (ESRD). We sought to examine access to waitlisting for kidney transplantation in a cohort spanning this policy change. Methods. This was a retrospective cohort analysis of 241,150 Medicare beneficiaries in the United States Renal Data System who initiated chronic dialysis between 1/1/96 and 11/30/03. We fit interrupted time series Cox proportional hazard models to compare access to kidney transplant waitlist within 12months of initiating chronic dialysis by age/disability status, accounting for secular trends. Results: Beneficiaries age <65 who were not disabled were less likely to be waitlisted after the policy change (hazard ratio (HR) for the later vs. earlier period, 0.93, p=0.002), after adjusting for sociodemographic factors, co-morbid conditions, income, and ESRD network. There was no evidence of secular trend in this group (HR per year, 1.00, p=0.989). Likelihood of being waitlisted among those age 65 or disabled increased steadily throughout the study period (HR per year, 1.04, p<0.001), but was not clearly affected by the policy change (HR for the immediate effect of policy change, 0.93, p=0.135). Conclusions: The most recent extension in Medicare immunosuppressant coverage appears to have had little impact on the already increasing access to waitlisting among 65/ disabled beneficiaries eligible for the benefit but may have decreased access for younger, non-disabled beneficiaries who were not. The potential ramifications of policies on candidacy appeal for access to kidney transplantation should be considered. © 2012Grubbs et al.; licensee BioMed Central Ltd. © 2012 Grubbs et al.; licensee BioMed Central Ltd.