A markedly increased incidence of cancer in renal transplant recipients is now recognized; to determine if immunosuppression alone may be responsible for this increase in risk, cancer incidence was compared in 709 renal transplant recipients and 317 dialysis patients. Malignancy developed in 19 transplant recipients (2.7%) and in 33 patients on chronic dialysis (10.4%). In our report an excess of skin cancer was observed in the transplant series while tumors of the urinary tract were seen more frequently in patients on dialysis. Transplantation and consecutive immunosuppression does not appear to constitute an additional cancer risk for the uremic patient who is faced with the alternative to undergo chronic dialysis or renal transplantation.