Between 1993 and 1995, Medicare extended its coverage of maintenance immunosuppression medications following renal transplantation from 1 to 3 years. We hypothesized that Medicare's extension of immunosuppressive coverage would improve graft survival among low-income transplant recipients. We merged patient-level clinical data from the USRDS-distributed UNOS registry of kidney transplants throughout the USA with median family income for each patient's ZIP code from the 1990 Census. We were able to merge median incomes to 10,837 first cadaveric renal transplants performed in 1992-93 and 16,732 performed in 1995-97. Each of these chronological cohorts was divided into two groups, those with family incomes above (high-income group) and those below (low-income group) $36,033. There were no differences in graft survival at 1 year based on income in either chronological era. However, when Medicare covered immunosuppression medications for just 1 year, the low-income group of 1-year graft survivors had a 4.5% lower graft survival at the end of 3 years post-transplant (p < 0.001). During the 1995-97 period, during which Medicare provided 3 years' immunosuppression coverage, the low-income and high-income groups had equivalent graft survival at 3 years post-transplant.