Renal cell carcinomas (RCCs) occur at an increased rate and at a younger age in patients with end-stage renal disease (ESRD) than in the general population. A papillary RCC from a patient with ESRD treated by hemodialysis and then by renal transplantation was karyotyped and showed a 55,XY,+2,+4,+7,+10,+12,+16,+17,+17,+20 mainline. No loss of gene sequences in the short arm of chromosome 3 was identified by chromosomal or molecular genetic analysis. Together with one prior report of a cytogenetic study of a RCC in an end-stage kidney, the findings indicate that papillary RCCs that arise in ESRD patients have genetic changes that are similar to those found in sporadic tumors. The increased frequency of tumors and the younger age of the patients may be due to an increased rate at which abnormal mitoses occur in diseased renal tissues.